Merge branch 'move-db-code'

56 files changed, 6481 insertions, 5185 deletions

diff --git a/src/gen_mod.erl b/src/gen_mod.erl
index 1044d095..a290aa20 100644
--- a/src/gen_mod.erl
+++ b/src/gen_mod.erl
@@ -36,7 +36,7 @@
 	 loaded_modules/1, loaded_modules_with_opts/1,
 	 get_hosts/2, get_module_proc/2, is_loaded/2,
 	 start_modules/0, start_modules/1, stop_modules/0, stop_modules/1,
-	 default_db/1, v_db/1, opt_type/1]).
+	 default_db/1, v_db/1, opt_type/1, db_mod/2, db_mod/3]).
 
 %%-export([behaviour_info/1]).
 
@@ -319,6 +319,19 @@ db_type(Host, Opts) when is_list(Opts) ->
 default_db(Host) ->
     ejabberd_config:get_option({default_db, Host}, fun v_db/1, mnesia).
 
+-spec db_mod(binary() | global | db_type(), module()) -> module().
+
+db_mod(odbc, Module) -> list_to_atom(atom_to_list(Module) ++ "_sql");
+db_mod(mnesia, Module) -> list_to_atom(atom_to_list(Module) ++ "_mnesia");
+db_mod(riak, Module) -> list_to_atom(atom_to_list(Module) ++ "_riak");
+db_mod(Host, Module) when is_binary(Host) orelse Host == global ->
+    db_mod(db_type(Host, Module), Module).
+
+-spec db_mod(binary() | global, opts(), module()) -> module().
+
+db_mod(Host, Opts, Module) when is_list(Opts) ->
+    db_mod(db_type(Host, Opts), Module).
+
 -spec loaded_modules(binary()) -> [atom()].
 
 loaded_modules(Host) ->
diff --git a/src/mod_announce.erl b/src/mod_announce.erl
index 0cf8c534..d7251c50 100644
--- a/src/mod_announce.erl
+++ b/src/mod_announce.erl
@@ -41,11 +41,16 @@
 -include("logger.hrl").
 -include("jlib.hrl").
 -include("adhoc.hrl").
+-include("mod_announce.hrl").
 
--record(motd, {server = <<"">> :: binary(),
-               packet = #xmlel{} :: xmlel()}).
--record(motd_users, {us = {<<"">>, <<"">>} :: {binary(), binary()} | '$1',
-                     dummy = [] :: [] | '_'}).
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #motd{} | #motd_users{}) -> ok | pass.
+-callback set_motd_users(binary(), [{binary(), binary(), binary()}]) -> {atomic, any()}.
+-callback set_motd(binary(), xmlel()) -> {atomic, any()}.
+-callback delete_motd(binary()) -> {atomic, any()}.
+-callback get_motd(binary()) -> {ok, xmlel()} | error.
+-callback is_motd_user(binary(), binary()) -> boolean().
+-callback set_motd_user(binary(), binary()) -> {atomic, any()}.
 
 -define(PROCNAME, ejabberd_announce).
 
@@ -55,20 +60,8 @@
 tokenize(Node) -> str:tokens(Node, <<"/#">>).
 
 start(Host, Opts) ->
-    case gen_mod:db_type(Host, Opts) of
-        mnesia ->
-            mnesia:create_table(motd,
-                                [{disc_copies, [node()]},
-                                 {attributes,
-                                  record_info(fields, motd)}]),
-            mnesia:create_table(motd_users,
-                                [{disc_copies, [node()]},
-                                 {attributes,
-                                  record_info(fields, motd_users)}]),
-            update_tables();
-        _ ->
-            ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     ejabberd_hooks:add(local_send_to_resource_hook, Host,
 		       ?MODULE, announce, 50),
     ejabberd_hooks:add(disco_local_identity, Host, ?MODULE, disco_identity, 50),
@@ -789,41 +782,8 @@ announce_motd(Host, Packet) ->
     announce_motd_update(LServer, Packet),
     Sessions = ejabberd_sm:get_vh_session_list(LServer),
     announce_online1(Sessions, LServer, Packet),
-    case gen_mod:db_type(LServer, ?MODULE) of
-        mnesia ->
-            F = fun() ->
-                        lists:foreach(
-                          fun({U, S, _R}) ->
-                                  mnesia:write(#motd_users{us = {U, S}})
-                          end, Sessions)
-                end,
-            mnesia:transaction(F);
-        riak ->
-            try
-                lists:foreach(
-                  fun({U, S, _R}) ->
-                          ok = ejabberd_riak:put(#motd_users{us = {U, S}},
-						 motd_users_schema(),
-                                                 [{'2i', [{<<"server">>, S}]}])
-                  end, Sessions),
-                {atomic, ok}
-            catch _:{badmatch, Err} ->
-                    {atomic, Err}
-            end;
-        odbc ->
-            F = fun() ->
-                        lists:foreach(
-                          fun({U, _S, _R}) ->
-                                  Username = ejabberd_odbc:escape(U),
-                                  odbc_queries:update_t(
-                                    <<"motd">>,
-                                    [<<"username">>, <<"xml">>],
-                                    [Username, <<"">>],
-                                    [<<"username='">>, Username, <<"'">>])
-                          end, Sessions)
-                end,
-            ejabberd_odbc:sql_transaction(LServer, F)
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:set_motd_users(LServer, Sessions).
 
 announce_motd_update(From, To, Packet) ->
     Host = To#jid.lserver,
@@ -853,27 +813,8 @@ announce_all_hosts_motd_update(From, To, Packet) ->
 
 announce_motd_update(LServer, Packet) ->
     announce_motd_delete(LServer),
-    case gen_mod:db_type(LServer, ?MODULE) of
-        mnesia ->
-            F = fun() ->
-                        mnesia:write(#motd{server = LServer, packet = Packet})
-                end,
-            mnesia:transaction(F);
-        riak ->
-            {atomic, ejabberd_riak:put(#motd{server = LServer,
-                                             packet = Packet},
-				       motd_schema())};
-        odbc ->
-            XML = ejabberd_odbc:escape(fxml:element_to_binary(Packet)),
-            F = fun() ->
-                        odbc_queries:update_t(
-                          <<"motd">>,
-                          [<<"username">>, <<"xml">>],
-                          [<<"">>, XML],
-                          [<<"username=''">>])
-                end,
-            ejabberd_odbc:sql_transaction(LServer, F)
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:set_motd(LServer, Packet).
 
 announce_motd_delete(From, To, Packet) ->
     Host = To#jid.lserver,
@@ -902,112 +843,30 @@ announce_all_hosts_motd_delete(From, To, Packet) ->
     end.
 
 announce_motd_delete(LServer) ->
-    case gen_mod:db_type(LServer, ?MODULE) of
-        mnesia ->
-            F = fun() ->
-                        mnesia:delete({motd, LServer}),
-                        mnesia:write_lock_table(motd_users),
-                        Users = mnesia:select(
-                                  motd_users,
-                                  [{#motd_users{us = '$1', _ = '_'},
-                                    [{'==', {element, 2, '$1'}, LServer}],
-                                    ['$1']}]),
-                        lists:foreach(fun(US) ->
-                                              mnesia:delete({motd_users, US})
-                                      end, Users)
-                end,
-            mnesia:transaction(F);
-        riak ->
-            try
-                ok = ejabberd_riak:delete(motd, LServer),
-                ok = ejabberd_riak:delete_by_index(motd_users,
-                                                   <<"server">>,
-                                                   LServer),
-                {atomic, ok}
-            catch _:{badmatch, Err} ->
-                    {atomic, Err}
-            end;
-        odbc ->
-            F = fun() ->
-                        ejabberd_odbc:sql_query_t([<<"delete from motd;">>])
-                end,
-            ejabberd_odbc:sql_transaction(LServer, F)
-    end.
-
-send_motd(JID) ->
-    send_motd(JID, gen_mod:db_type(JID#jid.lserver, ?MODULE)).
-
-send_motd(#jid{luser = LUser, lserver = LServer} = JID, mnesia) ->
-    case catch mnesia:dirty_read({motd, LServer}) of
-	[#motd{packet = Packet}] ->
-	    US = {LUser, LServer},
-	    case catch mnesia:dirty_read({motd_users, US}) of
-		[#motd_users{}] ->
-		    ok;
-		_ ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:delete_motd(LServer).
+
+send_motd(#jid{luser = LUser, lserver = LServer} = JID) when LUser /= <<>> ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:get_motd(LServer) of
+	{ok, Packet} ->
+	    case Mod:is_motd_user(LUser, LServer) of
+		false ->
 		    Local = jid:make(<<>>, LServer, <<>>),
 		    ejabberd_router:route(Local, JID, Packet),
-		    F = fun() ->
-				mnesia:write(#motd_users{us = US})
-			end,
-		    mnesia:transaction(F)
+		    Mod:set_motd_user(LUser, LServer);
+		true ->
+		    ok
 	    end;
-	_ ->
+	error ->
 	    ok
     end;
-send_motd(#jid{luser = LUser, lserver = LServer} = JID, riak) ->
-    case catch ejabberd_riak:get(motd, motd_schema(), LServer) of
-        {ok, #motd{packet = Packet}} ->
-            US = {LUser, LServer},
-            case ejabberd_riak:get(motd_users, motd_users_schema(), US) of
-                {ok, #motd_users{}} ->
-                    ok;
-                _ ->
-                    Local = jid:make(<<>>, LServer, <<>>),
-		    ejabberd_router:route(Local, JID, Packet),
-                    {atomic, ejabberd_riak:put(
-                               #motd_users{us = US}, motd_users_schema(),
-                               [{'2i', [{<<"server">>, LServer}]}])}
-            end;
-        _ ->
-            ok
-    end;
-send_motd(#jid{luser = LUser, lserver = LServer} = JID, odbc) when LUser /= <<>> ->
-    case catch ejabberd_odbc:sql_query(
-                 LServer, [<<"select xml from motd where username='';">>]) of
-        {selected, [<<"xml">>], [[XML]]} ->
-            case fxml_stream:parse_element(XML) of
-                {error, _} ->
-                    ok;
-                Packet ->
-                    Username = ejabberd_odbc:escape(LUser),
-                    case catch ejabberd_odbc:sql_query(
-                                 LServer,
-                                 [<<"select username from motd "
-                                    "where username='">>, Username, <<"';">>]) of
-                        {selected, [<<"username">>], []} ->
-                            Local = jid:make(<<"">>, LServer, <<"">>),
-                            ejabberd_router:route(Local, JID, Packet),
-                            F = fun() ->
-                                        odbc_queries:update_t(
-                                          <<"motd">>,
-                                          [<<"username">>, <<"xml">>],
-                                          [Username, <<"">>],
-                                          [<<"username='">>, Username, <<"'">>])
-                                end,
-                            ejabberd_odbc:sql_transaction(LServer, F);
-                        _ ->
-                            ok
-                    end
-            end;
-        _ ->
-            ok
-    end;
-send_motd(_, odbc) ->
+send_motd(_) ->
     ok.
 
 get_stored_motd(LServer) ->
-    case get_stored_motd_packet(LServer, gen_mod:db_type(LServer, ?MODULE)) of
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:get_motd(LServer) of
         {ok, Packet} ->
             {fxml:get_subtag_cdata(Packet, <<"subject">>),
              fxml:get_subtag_cdata(Packet, <<"body">>)};
@@ -1015,34 +874,6 @@ get_stored_motd(LServer) ->
             {<<>>, <<>>}
     end.
 
-get_stored_motd_packet(LServer, mnesia) ->
-    case catch mnesia:dirty_read({motd, LServer}) of
-	[#motd{packet = Packet}] ->
-            {ok, Packet};
-	_ ->
-	    error
-    end;
-get_stored_motd_packet(LServer, riak) ->
-    case ejabberd_riak:get(motd, motd_schema(), LServer) of
-        {ok, #motd{packet = Packet}} ->
-            {ok, Packet};
-	_ ->
-	    error
-    end;
-get_stored_motd_packet(LServer, odbc) ->
-    case catch ejabberd_odbc:sql_query(
-                 LServer, [<<"select xml from motd where username='';">>]) of
-        {selected, [<<"xml">>], [[XML]]} ->
-            case fxml_stream:parse_element(XML) of
-                {error, _} ->
-                    error;
-                Packet ->
-                    {ok, Packet}
-            end;
-        _ ->
-            error
-    end.
-
 %% This function is similar to others, but doesn't perform any ACL verification
 send_announcement_to_all(Host, SubjectS, BodyS) ->
     SubjectEls = if SubjectS /= <<>> ->
@@ -1076,96 +907,17 @@ get_access(Host) ->
                            none).
 
 %%-------------------------------------------------------------------------
-
-update_tables() ->
-    update_motd_table(),
-    update_motd_users_table().
-
-update_motd_table() ->
-    Fields = record_info(fields, motd),
-    case mnesia:table_info(motd, attributes) of
-	Fields ->
-            ejabberd_config:convert_table_to_binary(
-              motd, Fields, set,
-              fun(#motd{server = S}) -> S end,
-              fun(#motd{server = S, packet = P} = R) ->
-                      NewS = iolist_to_binary(S),
-                      NewP = fxml:to_xmlel(P),
-                      R#motd{server = NewS, packet = NewP}
-              end);
-	_ ->
-	    ?INFO_MSG("Recreating motd table", []),
-	    mnesia:transform_table(motd, ignore, Fields)
-    end.
-
-
-update_motd_users_table() ->
-    Fields = record_info(fields, motd_users),
-    case mnesia:table_info(motd_users, attributes) of
-	Fields ->
-	    ejabberd_config:convert_table_to_binary(
-              motd_users, Fields, set,
-              fun(#motd_users{us = {U, _}}) -> U end,
-              fun(#motd_users{us = {U, S}} = R) ->
-                      NewUS = {iolist_to_binary(U),
-                               iolist_to_binary(S)},
-                      R#motd_users{us = NewUS}
-              end);
-	_ ->
-	    ?INFO_MSG("Recreating motd_users table", []),
-	    mnesia:transform_table(motd_users, ignore, Fields)
-    end.
-
-motd_schema() ->
-    {record_info(fields, motd), #motd{}}.
-
-motd_users_schema() ->
-    {record_info(fields, motd_users), #motd_users{}}.
-
-export(_Server) ->
-    [{motd,
-      fun(Host, #motd{server = LServer, packet = El})
-            when LServer == Host ->
-              [[<<"delete from motd where username='';">>],
-               [<<"insert into motd(username, xml) values ('', '">>,
-                ejabberd_odbc:escape(fxml:element_to_binary(El)),
-                <<"');">>]];
-         (_Host, _R) ->
-              []
-      end},
-     {motd_users,
-      fun(Host, #motd_users{us = {LUser, LServer}})
-            when LServer == Host, LUser /= <<"">> ->
-              Username = ejabberd_odbc:escape(LUser),
-              [[<<"delete from motd where username='">>, Username, <<"';">>],
-               [<<"insert into motd(username, xml) values ('">>,
-                Username, <<"', '');">>]];
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select xml from motd where username='';">>,
-      fun([XML]) ->
-              El = fxml_stream:parse_element(XML),
-              #motd{server = LServer, packet = El}
-      end},
-     {<<"select username from motd where xml='';">>,
-      fun([LUser]) ->
-              #motd_users{us = {LUser, LServer}}
-      end}].
-
-import(_LServer, mnesia, #motd{} = Motd) ->
-    mnesia:dirty_write(Motd);
-import(_LServer, mnesia, #motd_users{} = Users) ->
-    mnesia:dirty_write(Users);
-import(_LServer, riak, #motd{} = Motd) ->
-    ejabberd_riak:put(Motd, motd_schema());
-import(_LServer, riak, #motd_users{us = {_, S}} = Users) ->
-    ejabberd_riak:put(Users, motd_users_schema(),
-		      [{'2i', [{<<"server">>, S}]}]);
-import(_, _, _) ->
-    pass.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
+
+import(LServer, DBType, LA) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, LA).
 
 mod_opt_type(access) ->
     fun (A) when is_atom(A) -> A end;
diff --git a/src/mod_announce_mnesia.erl b/src/mod_announce_mnesia.erl
new file mode 100644
index 00000000..c43eb853
--- /dev/null
+++ b/src/mod_announce_mnesia.erl
@@ -0,0 +1,129 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_announce_mnesia).
+-behaviour(mod_announce).
+
+%% API
+-export([init/2, set_motd_users/2, set_motd/2, delete_motd/1,
+	 get_motd/1, is_motd_user/2, set_motd_user/2, import/2]).
+
+-include("jlib.hrl").
+-include("mod_announce.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(motd,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, motd)}]),
+    mnesia:create_table(motd_users,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, motd_users)}]),
+    update_tables().
+
+set_motd_users(_LServer, USRs) ->
+    F = fun() ->
+		lists:foreach(
+		  fun({U, S, _R}) ->
+			  mnesia:write(#motd_users{us = {U, S}})
+		  end, USRs)
+	end,
+    mnesia:transaction(F).
+
+set_motd(LServer, Packet) ->
+    F = fun() ->
+		mnesia:write(#motd{server = LServer, packet = Packet})
+	end,
+    mnesia:transaction(F).
+
+delete_motd(LServer) ->
+    F = fun() ->
+		mnesia:delete({motd, LServer}),
+		mnesia:write_lock_table(motd_users),
+		Users = mnesia:select(
+			  motd_users,
+			  [{#motd_users{us = '$1', _ = '_'},
+			    [{'==', {element, 2, '$1'}, LServer}],
+			    ['$1']}]),
+		lists:foreach(fun(US) ->
+				      mnesia:delete({motd_users, US})
+			      end, Users)
+	end,
+    mnesia:transaction(F).
+
+get_motd(LServer) ->
+    case mnesia:dirty_read({motd, LServer}) of
+	[#motd{packet = Packet}] ->
+	    {ok, Packet};
+	_ ->
+	    error
+    end.
+
+is_motd_user(LUser, LServer) ->
+    case mnesia:dirty_read({motd_users, {LUser, LServer}}) of
+	[#motd_users{}] -> true;
+	_ -> false
+    end.
+
+set_motd_user(LUser, LServer) ->
+    F = fun() ->
+		mnesia:write(#motd_users{us = {LUser, LServer}})
+	end,
+    mnesia:transaction(F).
+
+import(_LServer, #motd{} = Motd) ->
+    mnesia:dirty_write(Motd);
+import(_LServer, #motd_users{} = Users) ->
+    mnesia:dirty_write(Users).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_tables() ->
+    update_motd_table(),
+    update_motd_users_table().
+
+update_motd_table() ->
+    Fields = record_info(fields, motd),
+    case mnesia:table_info(motd, attributes) of
+	Fields ->
+            ejabberd_config:convert_table_to_binary(
+              motd, Fields, set,
+              fun(#motd{server = S}) -> S end,
+              fun(#motd{server = S, packet = P} = R) ->
+                      NewS = iolist_to_binary(S),
+                      NewP = fxml:to_xmlel(P),
+                      R#motd{server = NewS, packet = NewP}
+              end);
+	_ ->
+	    ?INFO_MSG("Recreating motd table", []),
+	    mnesia:transform_table(motd, ignore, Fields)
+    end.
+
+
+update_motd_users_table() ->
+    Fields = record_info(fields, motd_users),
+    case mnesia:table_info(motd_users, attributes) of
+	Fields ->
+	    ejabberd_config:convert_table_to_binary(
+              motd_users, Fields, set,
+              fun(#motd_users{us = {U, _}}) -> U end,
+              fun(#motd_users{us = {U, S}} = R) ->
+                      NewUS = {iolist_to_binary(U),
+                               iolist_to_binary(S)},
+                      R#motd_users{us = NewUS}
+              end);
+	_ ->
+	    ?INFO_MSG("Recreating motd_users table", []),
+	    mnesia:transform_table(motd_users, ignore, Fields)
+    end.
diff --git a/src/mod_announce_riak.erl b/src/mod_announce_riak.erl
new file mode 100644
index 00000000..7ced0b3c
--- /dev/null
+++ b/src/mod_announce_riak.erl
@@ -0,0 +1,87 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_announce_riak).
+-behaviour(mod_announce).
+
+%% API
+-export([init/2, set_motd_users/2, set_motd/2, delete_motd/1,
+	 get_motd/1, is_motd_user/2, set_motd_user/2, import/2]).
+
+-include("jlib.hrl").
+-include("mod_announce.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+set_motd_users(_LServer, USRs) ->
+    try
+	lists:foreach(
+	  fun({U, S, _R}) ->
+		  ok = ejabberd_riak:put(#motd_users{us = {U, S}},
+					 motd_users_schema(),
+					 [{'2i', [{<<"server">>, S}]}])
+	  end, USRs),
+	{atomic, ok}
+    catch _:{badmatch, Err} ->
+	    {atomic, Err}
+    end.
+
+set_motd(LServer, Packet) ->
+    {atomic, ejabberd_riak:put(#motd{server = LServer,
+				     packet = Packet},
+			       motd_schema())}.
+
+delete_motd(LServer) ->
+    try
+	ok = ejabberd_riak:delete(motd, LServer),
+	ok = ejabberd_riak:delete_by_index(motd_users,
+					   <<"server">>,
+					   LServer),
+	{atomic, ok}
+    catch _:{badmatch, Err} ->
+	    {atomic, Err}
+    end.
+
+get_motd(LServer) ->
+    case ejabberd_riak:get(motd, motd_schema(), LServer) of
+        {ok, #motd{packet = Packet}} ->
+	    {ok, Packet};
+	_ ->
+	    error
+    end.
+
+is_motd_user(LUser, LServer) ->
+    case ejabberd_riak:get(motd_users, motd_users_schema(),
+			   {LUser, LServer}) of
+	{ok, #motd_users{}} -> true;
+	_ -> false
+    end.
+
+set_motd_user(LUser, LServer) ->
+    {atomic, ejabberd_riak:put(
+	       #motd_users{us = {LUser, LServer}}, motd_users_schema(),
+	       [{'2i', [{<<"server">>, LServer}]}])}.
+
+import(_LServer, #motd{} = Motd) ->
+    ejabberd_riak:put(Motd, motd_schema());
+import(_LServer, #motd_users{us = {_, S}} = Users) ->
+    ejabberd_riak:put(Users, motd_users_schema(),
+		      [{'2i', [{<<"server">>, S}]}]).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+motd_schema() ->
+    {record_info(fields, motd), #motd{}}.
+
+motd_users_schema() ->
+    {record_info(fields, motd_users), #motd_users{}}.
diff --git a/src/mod_announce_sql.erl b/src/mod_announce_sql.erl
new file mode 100644
index 00000000..cf10ffd8
--- /dev/null
+++ b/src/mod_announce_sql.erl
@@ -0,0 +1,132 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_announce_sql).
+-behaviour(mod_announce).
+
+%% API
+-export([init/2, set_motd_users/2, set_motd/2, delete_motd/1,
+	 get_motd/1, is_motd_user/2, set_motd_user/2, import/1,
+	 import/2, export/1]).
+
+-include("jlib.hrl").
+-include("mod_announce.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+set_motd_users(LServer, USRs) ->
+    F = fun() ->
+		lists:foreach(
+		  fun({U, _S, _R}) ->
+			  Username = ejabberd_odbc:escape(U),
+			  odbc_queries:update_t(
+			    <<"motd">>,
+			    [<<"username">>, <<"xml">>],
+			    [Username, <<"">>],
+			    [<<"username='">>, Username, <<"'">>])
+		  end, USRs)
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+set_motd(LServer, Packet) ->
+    XML = ejabberd_odbc:escape(fxml:element_to_binary(Packet)),
+    F = fun() ->
+		odbc_queries:update_t(
+		  <<"motd">>,
+		  [<<"username">>, <<"xml">>],
+		  [<<"">>, XML],
+		  [<<"username=''">>])
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+delete_motd(LServer) ->
+    F = fun() ->
+		ejabberd_odbc:sql_query_t([<<"delete from motd;">>])
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+get_motd(LServer) ->
+    case catch ejabberd_odbc:sql_query(
+                 LServer, [<<"select xml from motd where username='';">>]) of
+        {selected, [<<"xml">>], [[XML]]} ->
+            case fxml_stream:parse_element(XML) of
+                {error, _} ->
+                    error;
+                Packet ->
+		    {ok, Packet}
+	    end;
+	_ ->
+	    error
+    end.
+
+is_motd_user(LUser, LServer) ->
+    Username = ejabberd_odbc:escape(LUser),
+    case catch ejabberd_odbc:sql_query(
+		 LServer,
+		 [<<"select username from motd "
+		    "where username='">>, Username, <<"';">>]) of
+	{selected, [<<"username">>], [_|_]} ->
+	    true;
+	_ ->
+	    false
+    end.
+
+set_motd_user(LUser, LServer) ->
+    Username = ejabberd_odbc:escape(LUser),
+    F = fun() ->
+		odbc_queries:update_t(
+		  <<"motd">>,
+		  [<<"username">>, <<"xml">>],
+		  [Username, <<"">>],
+		  [<<"username='">>, Username, <<"'">>])
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+export(_Server) ->
+    [{motd,
+      fun(Host, #motd{server = LServer, packet = El})
+            when LServer == Host ->
+              [[<<"delete from motd where username='';">>],
+               [<<"insert into motd(username, xml) values ('', '">>,
+                ejabberd_odbc:escape(fxml:element_to_binary(El)),
+                <<"');">>]];
+         (_Host, _R) ->
+              []
+      end},
+     {motd_users,
+      fun(Host, #motd_users{us = {LUser, LServer}})
+            when LServer == Host, LUser /= <<"">> ->
+              Username = ejabberd_odbc:escape(LUser),
+              [[<<"delete from motd where username='">>, Username, <<"';">>],
+               [<<"insert into motd(username, xml) values ('">>,
+                Username, <<"', '');">>]];
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select xml from motd where username='';">>,
+      fun([XML]) ->
+              El = fxml_stream:parse_element(XML),
+              #motd{server = LServer, packet = El}
+      end},
+     {<<"select username from motd where xml='';">>,
+      fun([LUser]) ->
+              #motd_users{us = {LUser, LServer}}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_blocking.erl b/src/mod_blocking.erl
index d94b3090..af06e650 100644
--- a/src/mod_blocking.erl
+++ b/src/mod_blocking.erl
@@ -39,6 +39,10 @@
 
 -include("mod_privacy.hrl").
 
+-callback process_blocklist_block(binary(), binary(), function()) -> {atomic, any()}.
+-callback unblock_by_filter(binary(), binary(), function()) -> {atomic, any()}.
+-callback process_blocklist_get(binary(), binary()) -> [listitem()] | error.
+
 start(Host, Opts) ->
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
                              one_queue),
@@ -147,9 +151,8 @@ process_blocklist_block(LUser, LServer, JIDs, Lang) ->
 				 end,
 				 List, JIDs)
 	     end,
-    case process_blocklist_block_db(LUser, LServer, Filter,
-				    gen_mod:db_type(LServer, mod_privacy))
-	of
+    Mod = db_mod(LServer),
+    case Mod:process_blocklist_block(LUser, LServer, Filter) of
       {atomic, {ok, Default, List}} ->
 	  UserList = make_userlist(Default, List),
 	  broadcast_list_update(LUser, LServer, Default,
@@ -162,102 +165,14 @@ process_blocklist_block(LUser, LServer, JIDs, Lang) ->
 	    {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
     end.
 
-process_blocklist_block_db(LUser, LServer, Filter,
-			   mnesia) ->
-    F = fun () ->
-		case mnesia:wread({privacy, {LUser, LServer}}) of
-		  [] ->
-		      P = #privacy{us = {LUser, LServer}},
-		      NewDefault = <<"Blocked contacts">>,
-		      NewLists1 = [],
-		      List = [];
-		  [#privacy{default = Default, lists = Lists} = P] ->
-		      case lists:keysearch(Default, 1, Lists) of
-			{value, {_, List}} ->
-			    NewDefault = Default,
-			    NewLists1 = lists:keydelete(Default, 1, Lists);
-			false ->
-			    NewDefault = <<"Blocked contacts">>,
-			    NewLists1 = Lists,
-			    List = []
-		      end
-		end,
-		NewList = Filter(List),
-		NewLists = [{NewDefault, NewList} | NewLists1],
-		mnesia:write(P#privacy{default = NewDefault,
-				       lists = NewLists}),
-		{ok, NewDefault, NewList}
-	end,
-    mnesia:transaction(F);
-process_blocklist_block_db(LUser, LServer, Filter,
-			   riak) ->
-    {atomic,
-     begin
-         case ejabberd_riak:get(privacy, mod_privacy:privacy_schema(),
-				{LUser, LServer}) of
-             {ok, #privacy{default = Default, lists = Lists} = P} ->
-                 case lists:keysearch(Default, 1, Lists) of
-                     {value, {_, List}} ->
-                         NewDefault = Default,
-                         NewLists1 = lists:keydelete(Default, 1, Lists);
-                     false ->
-                         NewDefault = <<"Blocked contacts">>,
-                         NewLists1 = Lists,
-                         List = []
-                 end;
-             {error, _} ->
-                 P = #privacy{us = {LUser, LServer}},
-                 NewDefault = <<"Blocked contacts">>,
-                 NewLists1 = [],
-                 List = []
-         end,
-         NewList = Filter(List),
-         NewLists = [{NewDefault, NewList} | NewLists1],
-         case ejabberd_riak:put(P#privacy{default = NewDefault,
-                                          lists = NewLists},
-				mod_privacy:privacy_schema()) of
-             ok ->
-                 {ok, NewDefault, NewList};
-             Err ->
-                 Err
-         end
-     end};
-process_blocklist_block_db(LUser, LServer, Filter, odbc) ->
-    F = fun () ->
-		Default = case
-			    mod_privacy:sql_get_default_privacy_list_t(LUser)
-			      of
-			    {selected, []} ->
-				Name = <<"Blocked contacts">>,
-				mod_privacy:sql_add_privacy_list(LUser, Name),
-				mod_privacy:sql_set_default_privacy_list(LUser,
-									 Name),
-				Name;
-			    {selected, [{Name}]} -> Name
-			  end,
-		{selected, [{ID}]} =
-		    mod_privacy:sql_get_privacy_list_id_t(LUser, Default),
-		case mod_privacy:sql_get_privacy_list_data_by_id_t(ID) of
-		  {selected, RItems = [_ | _]} ->
-		      List = lists:flatmap(fun mod_privacy:raw_to_item/1, RItems);
-		  _ -> List = []
-		end,
-		NewList = Filter(List),
-		NewRItems = lists:map(fun mod_privacy:item_to_raw/1,
-				      NewList),
-		mod_privacy:sql_set_privacy_list(ID, NewRItems),
-		{ok, Default, NewList}
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
-
 process_blocklist_unblock_all(LUser, LServer, Lang) ->
     Filter = fun (List) ->
 		     lists:filter(fun (#listitem{action = A}) -> A =/= deny
 				  end,
 				  List)
 	     end,
-    DBType = gen_mod:db_type(LServer, mod_privacy),
-    case unblock_by_filter(LUser, LServer, Filter, DBType) of
+    Mod = db_mod(LServer),
+    case Mod:unblock_by_filter(LUser, LServer, Filter) of
       {atomic, ok} -> {result, []};
       {atomic, {ok, Default, List}} ->
 	  UserList = make_userlist(Default, List),
@@ -279,8 +194,8 @@ process_blocklist_unblock(LUser, LServer, JIDs, Lang) ->
 				  end,
 				  List)
 	     end,
-    DBType = gen_mod:db_type(LServer, mod_privacy),
-    case unblock_by_filter(LUser, LServer, Filter, DBType) of
+    Mod = db_mod(LServer),
+    case Mod:unblock_by_filter(LUser, LServer, Filter) of
       {atomic, ok} -> {result, []};
       {atomic, {ok, Default, List}} ->
 	  UserList = make_userlist(Default, List),
@@ -294,76 +209,6 @@ process_blocklist_unblock(LUser, LServer, JIDs, Lang) ->
 	    {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
     end.
 
-unblock_by_filter(LUser, LServer, Filter, mnesia) ->
-    F = fun () ->
-		case mnesia:read({privacy, {LUser, LServer}}) of
-		  [] ->
-		      % No lists, nothing to unblock
-		      ok;
-		  [#privacy{default = Default, lists = Lists} = P] ->
-		      case lists:keysearch(Default, 1, Lists) of
-			{value, {_, List}} ->
-			    NewList = Filter(List),
-			    NewLists1 = lists:keydelete(Default, 1, Lists),
-			    NewLists = [{Default, NewList} | NewLists1],
-			    mnesia:write(P#privacy{lists = NewLists}),
-			    {ok, Default, NewList};
-			false ->
-			    % No default list, nothing to unblock
-			    ok
-		      end
-		end
-	end,
-    mnesia:transaction(F);
-unblock_by_filter(LUser, LServer, Filter, riak) ->
-    {atomic,
-     case ejabberd_riak:get(privacy, mod_privacy:privacy_schema(),
-			    {LUser, LServer}) of
-         {error, _} ->
-             %% No lists, nothing to unblock
-             ok;
-         {ok, #privacy{default = Default, lists = Lists} = P} ->
-             case lists:keysearch(Default, 1, Lists) of
-                 {value, {_, List}} ->
-                     NewList = Filter(List),
-                     NewLists1 = lists:keydelete(Default, 1, Lists),
-                     NewLists = [{Default, NewList} | NewLists1],
-                     case ejabberd_riak:put(P#privacy{lists = NewLists},
-					    mod_privacy:privacy_schema()) of
-                         ok ->
-                             {ok, Default, NewList};
-                         Err ->
-                             Err
-                     end;
-                 false ->
-                     %% No default list, nothing to unblock
-                     ok
-             end
-     end};
-unblock_by_filter(LUser, LServer, Filter, odbc) ->
-    F = fun () ->
-		case mod_privacy:sql_get_default_privacy_list_t(LUser)
-		    of
-		  {selected, []} -> ok;
-		  {selected, [{Default}]} ->
-		      {selected, [{ID}]} =
-			  mod_privacy:sql_get_privacy_list_id_t(LUser, Default),
-		      case mod_privacy:sql_get_privacy_list_data_by_id_t(ID) of
-			{selected, RItems = [_ | _]} ->
-			    List = lists:flatmap(fun mod_privacy:raw_to_item/1,
-                                                 RItems),
-			    NewList = Filter(List),
-			    NewRItems = lists:map(fun mod_privacy:item_to_raw/1,
-						  NewList),
-			    mod_privacy:sql_set_privacy_list(ID, NewRItems),
-			    {ok, Default, NewList};
-			_ -> ok
-		      end;
-		  _ -> ok
-		end
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
-
 make_userlist(Name, List) ->
     NeedDb = mod_privacy:is_list_needdb(List),
     #userlist{name = Name, list = List, needdb = NeedDb}.
@@ -380,9 +225,8 @@ broadcast_blocklist_event(LUser, LServer, Event) ->
                       {broadcast, {blocking, Event}}).
 
 process_blocklist_get(LUser, LServer, Lang) ->
-    case process_blocklist_get_db(LUser, LServer,
-				  gen_mod:db_type(LServer, mod_privacy))
-	of
+    Mod = db_mod(LServer),
+    case Mod:process_blocklist_get(LUser, LServer) of
       error ->
 	  {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       List ->
@@ -402,45 +246,9 @@ process_blocklist_get(LUser, LServer, Lang) ->
 		   children = Items}]}
     end.
 
-process_blocklist_get_db(LUser, LServer, mnesia) ->
-    case catch mnesia:dirty_read(privacy, {LUser, LServer})
-	of
-      {'EXIT', _Reason} -> error;
-      [] -> [];
-      [#privacy{default = Default, lists = Lists}] ->
-	  case lists:keysearch(Default, 1, Lists) of
-	    {value, {_, List}} -> List;
-	    _ -> []
-	  end
-    end;
-process_blocklist_get_db(LUser, LServer, riak) ->
-    case ejabberd_riak:get(privacy, mod_privacy:privacy_schema(),
-			   {LUser, LServer}) of
-        {ok, #privacy{default = Default, lists = Lists}} ->
-            case lists:keysearch(Default, 1, Lists) of
-                {value, {_, List}} -> List;
-                _ -> []
-            end;
-        {error, notfound} ->
-            [];
-        {error, _} ->
-            error
-    end;
-process_blocklist_get_db(LUser, LServer, odbc) ->
-    case catch
-	   mod_privacy:sql_get_default_privacy_list(LUser, LServer)
-	of
-      {selected, []} -> [];
-      {selected, [{Default}]} ->
-	  case catch mod_privacy:sql_get_privacy_list_data(LUser,
-							   LServer, Default)
-	      of
-	    {selected, RItems} ->
-		lists:flatmap(fun mod_privacy:raw_to_item/1, RItems);
-	    {'EXIT', _} -> error
-	  end;
-      {'EXIT', _} -> error
-    end.
+db_mod(LServer) ->
+    DBType = gen_mod:db_type(LServer, mod_privacy),
+    gen_mod:db_mod(DBType, ?MODULE).
 
 mod_opt_type(iqdisc) -> fun gen_iq_handler:check_type/1;
 mod_opt_type(_) -> [iqdisc].
diff --git a/src/mod_blocking_mnesia.erl b/src/mod_blocking_mnesia.erl
new file mode 100644
index 00000000..5a4bde64
--- /dev/null
+++ b/src/mod_blocking_mnesia.erl
@@ -0,0 +1,85 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_blocking_mnesia).
+
+-behaviour(mod_blocking).
+
+%% API
+-export([process_blocklist_block/3, unblock_by_filter/3,
+	 process_blocklist_get/2]).
+
+-include("jlib.hrl").
+-include("mod_privacy.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+process_blocklist_block(LUser, LServer, Filter) ->
+    F = fun () ->
+		case mnesia:wread({privacy, {LUser, LServer}}) of
+		    [] ->
+			P = #privacy{us = {LUser, LServer}},
+			NewDefault = <<"Blocked contacts">>,
+			NewLists1 = [],
+			List = [];
+		    [#privacy{default = Default, lists = Lists} = P] ->
+			case lists:keysearch(Default, 1, Lists) of
+			    {value, {_, List}} ->
+				NewDefault = Default,
+				NewLists1 = lists:keydelete(Default, 1, Lists);
+			    false ->
+				NewDefault = <<"Blocked contacts">>,
+				NewLists1 = Lists,
+				List = []
+			end
+		end,
+		NewList = Filter(List),
+		NewLists = [{NewDefault, NewList} | NewLists1],
+		mnesia:write(P#privacy{default = NewDefault,
+				       lists = NewLists}),
+		{ok, NewDefault, NewList}
+	end,
+    mnesia:transaction(F).
+
+unblock_by_filter(LUser, LServer, Filter) ->
+    F = fun () ->
+		case mnesia:read({privacy, {LUser, LServer}}) of
+		    [] ->
+			%% No lists, nothing to unblock
+			ok;
+		    [#privacy{default = Default, lists = Lists} = P] ->
+			case lists:keysearch(Default, 1, Lists) of
+			    {value, {_, List}} ->
+				NewList = Filter(List),
+				NewLists1 = lists:keydelete(Default, 1, Lists),
+				NewLists = [{Default, NewList} | NewLists1],
+				mnesia:write(P#privacy{lists = NewLists}),
+				{ok, Default, NewList};
+			    false ->
+				%% No default list, nothing to unblock
+				ok
+			end
+		end
+	end,
+    mnesia:transaction(F).
+
+process_blocklist_get(LUser, LServer) ->
+    case catch mnesia:dirty_read(privacy, {LUser, LServer}) of
+	{'EXIT', _Reason} -> error;
+	[] -> [];
+	[#privacy{default = Default, lists = Lists}] ->
+	    case lists:keysearch(Default, 1, Lists) of
+		{value, {_, List}} -> List;
+		_ -> []
+	    end
+    end.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_blocking_riak.erl b/src/mod_blocking_riak.erl
new file mode 100644
index 00000000..5dd5cfa9
--- /dev/null
+++ b/src/mod_blocking_riak.erl
@@ -0,0 +1,98 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_blocking_riak).
+
+-behaviour(mod_blocking).
+
+%% API
+-export([process_blocklist_block/3, unblock_by_filter/3,
+	 process_blocklist_get/2]).
+
+-include("jlib.hrl").
+-include("mod_privacy.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+process_blocklist_block(LUser, LServer, Filter) ->
+    {atomic,
+     begin
+         case ejabberd_riak:get(privacy, mod_privacy_riak:privacy_schema(),
+				{LUser, LServer}) of
+             {ok, #privacy{default = Default, lists = Lists} = P} ->
+                 case lists:keysearch(Default, 1, Lists) of
+                     {value, {_, List}} ->
+                         NewDefault = Default,
+                         NewLists1 = lists:keydelete(Default, 1, Lists);
+                     false ->
+                         NewDefault = <<"Blocked contacts">>,
+                         NewLists1 = Lists,
+                         List = []
+                 end;
+             {error, _} ->
+                 P = #privacy{us = {LUser, LServer}},
+                 NewDefault = <<"Blocked contacts">>,
+                 NewLists1 = [],
+                 List = []
+         end,
+         NewList = Filter(List),
+         NewLists = [{NewDefault, NewList} | NewLists1],
+         case ejabberd_riak:put(P#privacy{default = NewDefault,
+                                          lists = NewLists},
+				mod_privacy_riak:privacy_schema()) of
+             ok ->
+                 {ok, NewDefault, NewList};
+             Err ->
+                 Err
+         end
+     end}.
+
+unblock_by_filter(LUser, LServer, Filter) ->
+    {atomic,
+     case ejabberd_riak:get(privacy, mod_privacy_riak:privacy_schema(),
+			    {LUser, LServer}) of
+         {error, _} ->
+             %% No lists, nothing to unblock
+             ok;
+         {ok, #privacy{default = Default, lists = Lists} = P} ->
+             case lists:keysearch(Default, 1, Lists) of
+                 {value, {_, List}} ->
+                     NewList = Filter(List),
+                     NewLists1 = lists:keydelete(Default, 1, Lists),
+                     NewLists = [{Default, NewList} | NewLists1],
+                     case ejabberd_riak:put(P#privacy{lists = NewLists},
+					    mod_privacy_riak:privacy_schema()) of
+                         ok ->
+                             {ok, Default, NewList};
+                         Err ->
+                             Err
+                     end;
+                 false ->
+                     %% No default list, nothing to unblock
+                     ok
+             end
+     end}.
+
+process_blocklist_get(LUser, LServer) ->
+    case ejabberd_riak:get(privacy, mod_privacy_riak:privacy_schema(),
+			   {LUser, LServer}) of
+        {ok, #privacy{default = Default, lists = Lists}} ->
+            case lists:keysearch(Default, 1, Lists) of
+                {value, {_, List}} -> List;
+                _ -> []
+            end;
+        {error, notfound} ->
+            [];
+        {error, _} ->
+            error
+    end.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_blocking_sql.erl b/src/mod_blocking_sql.erl
new file mode 100644
index 00000000..8177adae
--- /dev/null
+++ b/src/mod_blocking_sql.erl
@@ -0,0 +1,87 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_blocking_sql).
+
+-behaviour(mod_blocking).
+
+%% API
+-export([process_blocklist_block/3, unblock_by_filter/3,
+	 process_blocklist_get/2]).
+
+-include("jlib.hrl").
+-include("mod_privacy.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+process_blocklist_block(LUser, LServer, Filter) ->
+    F = fun () ->
+		Default = case mod_privacy_sql:sql_get_default_privacy_list_t(LUser) of
+			      {selected, []} ->
+				  Name = <<"Blocked contacts">>,
+				  mod_privacy_sql:sql_add_privacy_list(LUser, Name),
+				  mod_privacy_sql:sql_set_default_privacy_list(LUser, Name),
+				  Name;
+			      {selected, [{Name}]} -> Name
+			  end,
+		{selected, [{ID}]} =
+		    mod_privacy_sql:sql_get_privacy_list_id_t(LUser, Default),
+		case mod_privacy_sql:sql_get_privacy_list_data_by_id_t(ID) of
+		    {selected, RItems = [_ | _]} ->
+			List = lists:flatmap(fun mod_privacy_sql:raw_to_item/1, RItems);
+		    _ ->
+			List = []
+		end,
+		NewList = Filter(List),
+		NewRItems = lists:map(fun mod_privacy_sql:item_to_raw/1,
+				      NewList),
+		mod_privacy_sql:sql_set_privacy_list(ID, NewRItems),
+		{ok, Default, NewList}
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+unblock_by_filter(LUser, LServer, Filter) ->
+    F = fun () ->
+		case mod_privacy_sql:sql_get_default_privacy_list_t(LUser) of
+		    {selected, []} -> ok;
+		    {selected, [{Default}]} ->
+			{selected, [{ID}]} =
+			    mod_privacy_sql:sql_get_privacy_list_id_t(LUser, Default),
+			case mod_privacy_sql:sql_get_privacy_list_data_by_id_t(ID) of
+			    {selected, RItems = [_ | _]} ->
+				List = lists:flatmap(fun mod_privacy_sql:raw_to_item/1,
+						     RItems),
+				NewList = Filter(List),
+				NewRItems = lists:map(fun mod_privacy_sql:item_to_raw/1,
+						      NewList),
+				mod_privacy_sql:sql_set_privacy_list(ID, NewRItems),
+				{ok, Default, NewList};
+			    _ -> ok
+			end;
+		    _ -> ok
+		end
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+process_blocklist_get(LUser, LServer) ->
+    case catch mod_privacy_sql:sql_get_default_privacy_list(LUser, LServer) of
+	{selected, []} -> [];
+	{selected, [{Default}]} ->
+	    case catch mod_privacy_sql:sql_get_privacy_list_data(
+			 LUser, LServer, Default) of
+		{selected, RItems} ->
+		    lists:flatmap(fun mod_privacy_sql:raw_to_item/1, RItems);
+		{'EXIT', _} -> error
+	    end;
+	{'EXIT', _} -> error
+    end.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_caps.erl b/src/mod_caps.erl
index 0646d381..bd0f14f5 100644
--- a/src/mod_caps.erl
+++ b/src/mod_caps.erl
@@ -80,6 +80,12 @@
 
 -record(state, {host = <<"">> :: binary()}).
 
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback caps_read(binary(), {binary(), binary()}) ->
+    {ok, non_neg_integer() | [binary()]} | error.
+-callback caps_write(binary(), {binary(), binary()},
+		     non_neg_integer() | [binary()]) -> any().
+
 start_link(Host, Opts) ->
     Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
     gen_server:start_link({local, Proc}, ?MODULE,
@@ -300,28 +306,9 @@ c2s_broadcast_recipients(InAcc, Host, C2SState,
     end;
 c2s_broadcast_recipients(Acc, _, _, _, _, _) -> Acc.
 
-init_db(mnesia, _Host) ->
-    case catch mnesia:table_info(caps_features, storage_type) of
-        {'EXIT', _} ->
-            ok;
-        disc_only_copies ->
-            ok;
-        _ ->
-            mnesia:delete_table(caps_features)
-    end,
-    mnesia:create_table(caps_features,
-                        [{disc_only_copies, [node()]},
-                         {local_content, true},
-                         {attributes,
-                          record_info(fields, caps_features)}]),
-    update_table(),
-    mnesia:add_table_copy(caps_features, node(),
-                          disc_only_copies);
-init_db(_, _) ->
-    ok.
-
 init([Host, Opts]) ->
-    init_db(gen_mod:db_type(Host, Opts), Host),
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     MaxSize = gen_mod:get_opt(cache_size, Opts,
                               fun(I) when is_integer(I), I>0 -> I end,
                               1000),
@@ -450,65 +437,13 @@ feature_response(_IQResult, Host, From, Caps,
 
 caps_read_fun(Host, Node) ->
     LServer = jid:nameprep(Host),
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    caps_read_fun(LServer, Node, DBType).
-
-caps_read_fun(_LServer, Node, mnesia) ->
-    fun () ->
-	    case mnesia:dirty_read({caps_features, Node}) of
-	      [#caps_features{features = Features}] -> {ok, Features};
-	      _ -> error
-	    end
-    end;
-caps_read_fun(_LServer, Node, riak) ->
-    fun() ->
-            case ejabberd_riak:get(caps_features, caps_features_schema(), Node) of
-                {ok, #caps_features{features = Features}} -> {ok, Features};
-                _ -> error
-            end
-    end;
-caps_read_fun(LServer, {Node, SubNode}, odbc) ->
-    fun() ->
-            SNode = ejabberd_odbc:escape(Node),
-            SSubNode = ejabberd_odbc:escape(SubNode),
-            case ejabberd_odbc:sql_query(
-                   LServer, [<<"select feature from caps_features where ">>,
-                             <<"node='">>, SNode, <<"' and subnode='">>,
-                             SSubNode, <<"';">>]) of
-                {selected, [<<"feature">>], [[H]|_] = Fs} ->
-                    case catch jlib:binary_to_integer(H) of
-                        Int when is_integer(Int), Int>=0 ->
-                            {ok, Int};
-                        _ ->
-                            {ok, lists:flatten(Fs)}
-                    end;
-                _ ->
-                    error
-            end
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    fun() -> Mod:caps_read(LServer, Node) end.
 
 caps_write_fun(Host, Node, Features) ->
     LServer = jid:nameprep(Host),
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    caps_write_fun(LServer, Node, Features, DBType).
-
-caps_write_fun(_LServer, Node, Features, mnesia) ->
-    fun () ->
-	    mnesia:dirty_write(#caps_features{node_pair = Node,
-					      features = Features})
-    end;
-caps_write_fun(_LServer, Node, Features, riak) ->
-    fun () ->
-            ejabberd_riak:put(#caps_features{node_pair = Node,
-                                             features = Features},
-			      caps_features_schema())
-    end;
-caps_write_fun(LServer, NodePair, Features, odbc) ->
-    fun () ->
-            ejabberd_odbc:sql_transaction(
-              LServer,
-              sql_write_features_t(NodePair, Features))
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    fun() -> Mod:caps_write(LServer, Node, Features) end.
 
 make_my_disco_hash(Host) ->
     JID = jid:make(<<"">>, Host, <<"">>),
@@ -658,61 +593,20 @@ is_valid_node(Node) ->
             false
     end.
 
-update_table() ->
-    Fields = record_info(fields, caps_features),
-    case mnesia:table_info(caps_features, attributes) of
-        Fields ->
-            ejabberd_config:convert_table_to_binary(
-              caps_features, Fields, set,
-              fun(#caps_features{node_pair = {N, _}}) -> N end,
-              fun(#caps_features{node_pair = {N, P},
-                                 features = Fs} = R) ->
-                      NewFs = if is_integer(Fs) ->
-                                      Fs;
-                                 true ->
-                                      [iolist_to_binary(F) || F <- Fs]
-                              end,
-                      R#caps_features{node_pair = {iolist_to_binary(N),
-                                                   iolist_to_binary(P)},
-                                      features = NewFs}
-              end);
-        _ ->
-            ?INFO_MSG("Recreating caps_features table", []),
-            mnesia:transform_table(caps_features, ignore, Fields)
-    end.
-
-sql_write_features_t({Node, SubNode}, Features) ->
-    SNode = ejabberd_odbc:escape(Node),
-    SSubNode = ejabberd_odbc:escape(SubNode),
-    NewFeatures = if is_integer(Features) ->
-                          [jlib:integer_to_binary(Features)];
-                     true ->
-                          Features
-                  end,
-    [[<<"delete from caps_features where node='">>,
-      SNode, <<"' and subnode='">>, SSubNode, <<"';">>]|
-     [[<<"insert into caps_features(node, subnode, feature) ">>,
-       <<"values ('">>, SNode, <<"', '">>, SSubNode, <<"', '">>,
-       ejabberd_odbc:escape(F), <<"');">>] || F <- NewFeatures]].
-
 caps_features_schema() ->
     {record_info(fields, caps_features), #caps_features{}}.
 
-export(_Server) ->
-    [{caps_features,
-      fun(_Host, #caps_features{node_pair = NodePair,
-                                features = Features}) ->
-              sql_write_features_t(NodePair, Features);
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import_info() ->
     [{<<"caps_features">>, 4}].
 
 import_start(LServer, DBType) ->
     ets:new(caps_features_tmp, [private, named_table, bag]),
-    init_db(DBType, LServer),
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:init(LServer, []),
     ok.
 
 import(_LServer, {odbc, _}, _DBType, <<"caps_features">>,
diff --git a/src/mod_caps_mnesia.erl b/src/mod_caps_mnesia.erl
new file mode 100644
index 00000000..0bf04b2c
--- /dev/null
+++ b/src/mod_caps_mnesia.erl
@@ -0,0 +1,73 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_caps_mnesia).
+-behaviour(mod_caps).
+
+%% API
+-export([init/2, caps_read/2, caps_write/3]).
+
+-include("mod_caps.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    case catch mnesia:table_info(caps_features, storage_type) of
+        {'EXIT', _} ->
+            ok;
+        disc_only_copies ->
+            ok;
+        _ ->
+            mnesia:delete_table(caps_features)
+    end,
+    mnesia:create_table(caps_features,
+                        [{disc_only_copies, [node()]},
+                         {local_content, true},
+                         {attributes,
+                          record_info(fields, caps_features)}]),
+    update_table(),
+    mnesia:add_table_copy(caps_features, node(),
+                          disc_only_copies).
+
+caps_read(_LServer, Node) ->
+    case mnesia:dirty_read({caps_features, Node}) of
+	[#caps_features{features = Features}] -> {ok, Features};
+	_ -> error
+    end.
+
+caps_write(_LServer, Node, Features) ->
+    mnesia:dirty_write(#caps_features{node_pair = Node,
+				      features = Features}).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_table() ->
+    Fields = record_info(fields, caps_features),
+    case mnesia:table_info(caps_features, attributes) of
+        Fields ->
+            ejabberd_config:convert_table_to_binary(
+              caps_features, Fields, set,
+              fun(#caps_features{node_pair = {N, _}}) -> N end,
+              fun(#caps_features{node_pair = {N, P},
+                                 features = Fs} = R) ->
+                      NewFs = if is_integer(Fs) ->
+                                      Fs;
+                                 true ->
+                                      [iolist_to_binary(F) || F <- Fs]
+                              end,
+                      R#caps_features{node_pair = {iolist_to_binary(N),
+                                                   iolist_to_binary(P)},
+                                      features = NewFs}
+              end);
+        _ ->
+            ?INFO_MSG("Recreating caps_features table", []),
+            mnesia:transform_table(caps_features, ignore, Fields)
+    end.
diff --git a/src/mod_caps_riak.erl b/src/mod_caps_riak.erl
new file mode 100644
index 00000000..6e59ba86
--- /dev/null
+++ b/src/mod_caps_riak.erl
@@ -0,0 +1,38 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_caps_riak).
+-behaviour(mod_caps).
+
+%% API
+-export([init/2, caps_read/2, caps_write/3]).
+
+-include("mod_caps.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+caps_read(_LServer, Node) ->
+    case ejabberd_riak:get(caps_features, caps_features_schema(), Node) of
+	{ok, #caps_features{features = Features}} -> {ok, Features};
+	_ -> error
+    end.
+
+caps_write(_LServer, Node, Features) ->
+    ejabberd_riak:put(#caps_features{node_pair = Node,
+				     features = Features},
+		      caps_features_schema()).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+caps_features_schema() ->
+    {record_info(fields, caps_features), #caps_features{}}.
diff --git a/src/mod_caps_sql.erl b/src/mod_caps_sql.erl
new file mode 100644
index 00000000..353b95b1
--- /dev/null
+++ b/src/mod_caps_sql.erl
@@ -0,0 +1,71 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_caps_sql).
+-behaviour(mod_caps).
+
+%% API
+-export([init/2, caps_read/2, caps_write/3, export/1]).
+
+-include("mod_caps.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+caps_read(LServer, {Node, SubNode}) ->
+    SNode = ejabberd_odbc:escape(Node),
+    SSubNode = ejabberd_odbc:escape(SubNode),
+    case ejabberd_odbc:sql_query(
+	   LServer, [<<"select feature from caps_features where ">>,
+		     <<"node='">>, SNode, <<"' and subnode='">>,
+		     SSubNode, <<"';">>]) of
+	{selected, [<<"feature">>], [[H]|_] = Fs} ->
+	    case catch jlib:binary_to_integer(H) of
+		Int when is_integer(Int), Int>=0 ->
+		    {ok, Int};
+		_ ->
+		    {ok, lists:flatten(Fs)}
+	    end;
+	_ ->
+	    error
+    end.
+
+caps_write(LServer, NodePair, Features) ->
+    ejabberd_odbc:sql_transaction(
+      LServer,
+      sql_write_features_t(NodePair, Features)).
+
+export(_Server) ->
+    [{caps_features,
+      fun(_Host, #caps_features{node_pair = NodePair,
+                                features = Features}) ->
+              sql_write_features_t(NodePair, Features);
+         (_Host, _R) ->
+              []
+      end}].
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+sql_write_features_t({Node, SubNode}, Features) ->
+    SNode = ejabberd_odbc:escape(Node),
+    SSubNode = ejabberd_odbc:escape(SubNode),
+    NewFeatures = if is_integer(Features) ->
+                          [jlib:integer_to_binary(Features)];
+                     true ->
+                          Features
+                  end,
+    [[<<"delete from caps_features where node='">>,
+      SNode, <<"' and subnode='">>, SSubNode, <<"';">>]|
+     [[<<"insert into caps_features(node, subnode, feature) ">>,
+       <<"values ('">>, SNode, <<"', '">>, SSubNode, <<"', '">>,
+       ejabberd_odbc:escape(F), <<"');">>] || F <- NewFeatures]].
+
diff --git a/src/mod_irc.erl b/src/mod_irc.erl
index f6e452d8..e0c658de 100644
--- a/src/mod_irc.erl
+++ b/src/mod_irc.erl
@@ -33,7 +33,8 @@
 
 %% API
 -export([start_link/2, start/2, stop/1, export/1, import/1,
-	 import/3, closed_connection/3, get_connection_params/3]).
+	 import/3, closed_connection/3, get_connection_params/3,
+	 data_to_binary/2]).
 
 -export([init/1, handle_call/3, handle_cast/2,
 	 handle_info/2, terminate/2, code_change/3,
@@ -46,6 +47,8 @@
 
 -include("adhoc.hrl").
 
+-include("mod_irc.hrl").
+
 -define(DEFAULT_IRC_ENCODING, <<"iso8859-15">>).
 
 -define(DEFAULT_IRC_PORT, 6667).
@@ -58,27 +61,19 @@
 	[<<"koi8-r">>, <<"iso8859-15">>, <<"iso8859-1">>, <<"iso8859-2">>,
 	 <<"utf-8">>, <<"utf-8+latin-1">>]).
 
--type conn_param() :: {binary(), binary(), inet:port_number(), binary()} |
-                      {binary(), binary(), inet:port_number()} |
-                      {binary(), binary()} |
-                      {binary()}.
-
--record(irc_connection,
-        {jid_server_host = {#jid{}, <<"">>, <<"">>} :: {jid(), binary(), binary()},
-         pid = self()                               :: pid()}).
-
--record(irc_custom,
-        {us_host = {{<<"">>, <<"">>}, <<"">>} :: {{binary(), binary()},
-                                                  binary()},
-         data = [] :: [{username, binary()} |
-                       {connections_params, [conn_param()]}]}).
-
 -record(state, {host = <<"">>        :: binary(),
                 server_host = <<"">> :: binary(),
                 access = all         :: atom()}).
 
 -define(PROCNAME, ejabberd_mod_irc).
 
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #irc_custom{}) -> ok | pass.
+-callback get_data(binary(), binary(), {binary(), binary()}) ->
+    error | empty | irc_data().
+-callback set_data(binary(), binary(), {binary(), binary()}, irc_data()) ->
+    {atomic, any()}.
+
 %%====================================================================
 %% API
 %%====================================================================
@@ -119,14 +114,8 @@ init([Host, Opts]) ->
     ejabberd:start_app(iconv),
     MyHost = gen_mod:get_opt_host(Host, Opts,
 				  <<"irc.@HOST@">>),
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(irc_custom,
-			      [{disc_copies, [node()]},
-			       {attributes, record_info(fields, irc_custom)}]),
-	  update_table();
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     Access = gen_mod:get_opt(access, Opts,
                              fun(A) when is_atom(A) -> A end,
                              all),
@@ -597,43 +586,8 @@ process_irc_register(ServerHost, Host, From, _To,
 
 get_data(ServerHost, Host, From) ->
     LServer = jid:nameprep(ServerHost),
-    get_data(LServer, Host, From,
-             gen_mod:db_type(LServer, ?MODULE)).
-
-get_data(_LServer, Host, From, mnesia) ->
-    #jid{luser = LUser, lserver = LServer} = From,
-    US = {LUser, LServer},
-    case catch mnesia:dirty_read({irc_custom, {US, Host}})
-	of
-      {'EXIT', _Reason} -> error;
-      [] -> empty;
-      [#irc_custom{data = Data}] -> Data
-    end;
-get_data(LServer, Host, From, riak) ->
-    #jid{luser = LUser, lserver = LServer} = From,
-    US = {LUser, LServer},
-    case ejabberd_riak:get(irc_custom, irc_custom_schema(), {US, Host}) of
-        {ok, #irc_custom{data = Data}} ->
-            Data;
-        {error, notfound} ->
-            empty;
-        _Err ->
-            error
-    end;
-get_data(LServer, Host, From, odbc) ->
-    SJID =
-	ejabberd_odbc:escape(jid:to_string(jid:tolower(jid:remove_resource(From)))),
-    SHost = ejabberd_odbc:escape(Host),
-    case catch ejabberd_odbc:sql_query(LServer,
-				       [<<"select data from irc_custom where jid='">>,
-					SJID, <<"' and host='">>, SHost,
-					<<"';">>])
-	of
-      {selected, [<<"data">>], [[SData]]} ->
-	  data_to_binary(From, ejabberd_odbc:decode_term(SData));
-      {'EXIT', _} -> error;
-      {selected, _, _} -> empty
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_data(LServer, Host, From).
 
 get_form(ServerHost, Host, From, [], Lang) ->
     #jid{user = User, server = Server} = From,
@@ -743,37 +697,8 @@ get_form(_ServerHost, _Host, _, _, _Lang) ->
 
 set_data(ServerHost, Host, From, Data) ->
     LServer = jid:nameprep(ServerHost),
-    set_data(LServer, Host, From, data_to_binary(From, Data),
-	     gen_mod:db_type(LServer, ?MODULE)).
-
-set_data(_LServer, Host, From, Data, mnesia) ->
-    {LUser, LServer, _} = jid:tolower(From),
-    US = {LUser, LServer},
-    F = fun () ->
-		mnesia:write(#irc_custom{us_host = {US, Host},
-					 data = Data})
-	end,
-    mnesia:transaction(F);
-set_data(LServer, Host, From, Data, riak) ->
-    {LUser, LServer, _} = jid:tolower(From),
-    US = {LUser, LServer},
-    {atomic, ejabberd_riak:put(#irc_custom{us_host = {US, Host},
-                                           data = Data},
-			       irc_custom_schema())};
-set_data(LServer, Host, From, Data, odbc) ->
-    SJID =
-	ejabberd_odbc:escape(jid:to_string(jid:tolower(jid:remove_resource(From)))),
-    SHost = ejabberd_odbc:escape(Host),
-    SData = ejabberd_odbc:encode_term(Data),
-    F = fun () ->
-		odbc_queries:update_t(<<"irc_custom">>,
-				      [<<"jid">>, <<"host">>, <<"data">>],
-				      [SJID, SHost, SData],
-				      [<<"jid='">>, SJID, <<"' and host='">>,
-				       SHost, <<"'">>]),
-		ok
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:set_data(LServer, Host, From, data_to_binary(From, Data)).
 
 set_form(ServerHost, Host, From, [], Lang, XData) ->
     case {lists:keysearch(<<"username">>, 1, XData),
@@ -1314,66 +1239,17 @@ conn_params_to_list(Params) ->
                Port, binary_to_list(P)}
       end, Params).
 
-irc_custom_schema() ->
-    {record_info(fields, irc_custom), #irc_custom{}}.
-
-update_table() ->
-    Fields = record_info(fields, irc_custom),
-    case mnesia:table_info(irc_custom, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            irc_custom, Fields, set,
-            fun(#irc_custom{us_host = {_, H}}) -> H end,
-            fun(#irc_custom{us_host = {{U, S}, H},
-                            data = Data} = R) ->
-		    JID = jid:make(U, S, <<"">>),
-                    R#irc_custom{us_host = {{iolist_to_binary(U),
-                                             iolist_to_binary(S)},
-                                            iolist_to_binary(H)},
-                                 data = data_to_binary(JID, Data)}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating irc_custom table", []),
-	  mnesia:transform_table(irc_custom, ignore, Fields)
-    end.
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
-export(_Server) ->
-    [{irc_custom,
-      fun(Host, #irc_custom{us_host = {{U, S}, IRCHost},
-                            data = Data}) ->
-              case str:suffix(Host, IRCHost) of
-                  true ->
-                      SJID = ejabberd_odbc:escape(
-                               jid:to_string(
-                                 jid:make(U, S, <<"">>))),
-                      SIRCHost = ejabberd_odbc:escape(IRCHost),
-                      SData = ejabberd_odbc:encode_term(Data),
-                      [[<<"delete from irc_custom where jid='">>, SJID,
-                        <<"' and host='">>, SIRCHost, <<"';">>],
-                       [<<"insert into irc_custom(jid, host, "
-                          "data) values ('">>,
-                        SJID, <<"', '">>, SIRCHost, <<"', '">>, SData,
-                        <<"');">>]];
-                  false ->
-                      []
-              end
-      end}].
-
-import(_LServer) ->
-    [{<<"select jid, host, data from irc_custom;">>,
-      fun([SJID, IRCHost, SData]) ->
-              #jid{luser = U, lserver = S} = jid:from_string(SJID),
-              Data = ejabberd_odbc:decode_term(SData),
-              #irc_custom{us_host = {{U, S}, IRCHost},
-                          data = Data}
-      end}].
+import(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
 
-import(_LServer, mnesia, #irc_custom{} = R) ->
-    mnesia:dirty_write(R);
-import(_LServer, riak, #irc_custom{} = R) ->
-    ejabberd_riak:put(R, irc_custom_schema());
-import(_, _, _) ->
-    pass.
+import(LServer, DBType, Data) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, Data).
 
 mod_opt_type(access) ->
     fun (A) when is_atom(A) -> A end;
diff --git a/src/mod_irc_mnesia.erl b/src/mod_irc_mnesia.erl
new file mode 100644
index 00000000..9f8117ad
--- /dev/null
+++ b/src/mod_irc_mnesia.erl
@@ -0,0 +1,69 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_irc_mnesia).
+
+-behaviour(mod_irc).
+
+%% API
+-export([init/2, get_data/3, set_data/4, import/2]).
+
+-include("jlib.hrl").
+-include("mod_irc.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(irc_custom,
+			[{disc_copies, [node()]},
+			 {attributes, record_info(fields, irc_custom)}]),
+    update_table().
+
+get_data(_LServer, Host, From) ->
+    {U, S, _} = jid:tolower(From),
+    case catch mnesia:dirty_read({irc_custom, {{U, S}, Host}}) of
+	{'EXIT', _Reason} -> error;
+	[] -> empty;
+	[#irc_custom{data = Data}] -> Data
+    end.
+
+set_data(_LServer, Host, From, Data) ->
+    {U, S, _} = jid:tolower(From),
+    F = fun () ->
+		mnesia:write(#irc_custom{us_host = {{U, S}, Host},
+					 data = Data})
+	end,
+    mnesia:transaction(F).
+
+import(_LServer, #irc_custom{} = R) ->
+    mnesia:dirty_write(R).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_table() ->
+    Fields = record_info(fields, irc_custom),
+    case mnesia:table_info(irc_custom, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            irc_custom, Fields, set,
+            fun(#irc_custom{us_host = {_, H}}) -> H end,
+            fun(#irc_custom{us_host = {{U, S}, H},
+                            data = Data} = R) ->
+		    JID = jid:make(U, S, <<"">>),
+                    R#irc_custom{us_host = {{iolist_to_binary(U),
+                                             iolist_to_binary(S)},
+                                            iolist_to_binary(H)},
+                                 data = mod_irc:data_to_binary(JID, Data)}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating irc_custom table", []),
+	  mnesia:transform_table(irc_custom, ignore, Fields)
+    end.
diff --git a/src/mod_irc_riak.erl b/src/mod_irc_riak.erl
new file mode 100644
index 00000000..6ac7befd
--- /dev/null
+++ b/src/mod_irc_riak.erl
@@ -0,0 +1,49 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_irc_riak).
+
+-behaviour(mod_irc).
+
+%% API
+-export([init/2, get_data/3, set_data/4, import/2]).
+
+-include("jlib.hrl").
+-include("mod_irc.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+get_data(_LServer, Host, From) ->
+    {U, S, _} = jid:tolower(From),
+    case ejabberd_riak:get(irc_custom, irc_custom_schema(), {{U, S}, Host}) of
+        {ok, #irc_custom{data = Data}} ->
+            Data;
+        {error, notfound} ->
+            empty;
+        _Err ->
+            error
+    end.
+
+set_data(_LServer, Host, From, Data) ->
+    {U, S, _} = jid:tolower(From),
+    {atomic, ejabberd_riak:put(#irc_custom{us_host = {{U, S}, Host},
+                                           data = Data},
+			       irc_custom_schema())}.
+
+import(_LServer, #irc_custom{} = R) ->
+    ejabberd_riak:put(R, irc_custom_schema()).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+irc_custom_schema() ->
+    {record_info(fields, irc_custom), #irc_custom{}}.
diff --git a/src/mod_irc_sql.erl b/src/mod_irc_sql.erl
new file mode 100644
index 00000000..bf6dbb48
--- /dev/null
+++ b/src/mod_irc_sql.erl
@@ -0,0 +1,91 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_irc_sql).
+
+-behaviour(mod_irc).
+
+%% API
+-export([init/2, get_data/3, set_data/4, import/1, import/2, export/1]).
+
+-include("jlib.hrl").
+-include("mod_irc.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+get_data(LServer, Host, From) ->
+    LJID = jid:tolower(jid:remove_resource(From)),
+    SJID = ejabberd_odbc:escape(jid:to_string(LJID)),
+    SHost = ejabberd_odbc:escape(Host),
+    case catch ejabberd_odbc:sql_query(
+		 LServer,
+		 [<<"select data from irc_custom where jid='">>,
+		  SJID, <<"' and host='">>, SHost,
+		  <<"';">>]) of
+	{selected, [<<"data">>], [[SData]]} ->
+	    mod_irc:data_to_binary(From, ejabberd_odbc:decode_term(SData));
+	{'EXIT', _} -> error;
+	{selected, _, _} -> empty
+    end.
+
+set_data(LServer, Host, From, Data) ->
+    LJID = jid:tolower(jid:remove_resource(From)),
+    SJID = ejabberd_odbc:escape(jid:to_string(LJID)),
+    SHost = ejabberd_odbc:escape(Host),
+    SData = ejabberd_odbc:encode_term(Data),
+    F = fun () ->
+		odbc_queries:update_t(<<"irc_custom">>,
+				      [<<"jid">>, <<"host">>, <<"data">>],
+				      [SJID, SHost, SData],
+				      [<<"jid='">>, SJID, <<"' and host='">>,
+				       SHost, <<"'">>]),
+		ok
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+export(_Server) ->
+    [{irc_custom,
+      fun(Host, #irc_custom{us_host = {{U, S}, IRCHost},
+                            data = Data}) ->
+              case str:suffix(Host, IRCHost) of
+                  true ->
+                      SJID = ejabberd_odbc:escape(
+                               jid:to_string(
+                                 jid:make(U, S, <<"">>))),
+                      SIRCHost = ejabberd_odbc:escape(IRCHost),
+                      SData = ejabberd_odbc:encode_term(Data),
+                      [[<<"delete from irc_custom where jid='">>, SJID,
+                        <<"' and host='">>, SIRCHost, <<"';">>],
+                       [<<"insert into irc_custom(jid, host, "
+                          "data) values ('">>,
+                        SJID, <<"', '">>, SIRCHost, <<"', '">>, SData,
+                        <<"');">>]];
+                  false ->
+                      []
+              end
+      end}].
+
+import(_LServer) ->
+    [{<<"select jid, host, data from irc_custom;">>,
+      fun([SJID, IRCHost, SData]) ->
+              #jid{luser = U, lserver = S} = jid:from_string(SJID),
+              Data = ejabberd_odbc:decode_term(SData),
+              #irc_custom{us_host = {{U, S}, IRCHost},
+                          data = Data}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_last.erl b/src/mod_last.erl
index 009a1cb0..1af1847b 100644
--- a/src/mod_last.erl
+++ b/src/mod_last.erl
@@ -45,23 +45,21 @@
 -include("jlib.hrl").
 
 -include("mod_privacy.hrl").
+-include("mod_last.hrl").
 
--record(last_activity, {us = {<<"">>, <<"">>} :: {binary(), binary()},
-                        timestamp = 0 :: non_neg_integer(),
-                        status = <<"">> :: binary()}).
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #last_activity{}) -> ok | pass.
+-callback get_last(binary(), binary()) ->
+    {ok, non_neg_integer(), binary()} | not_found | {error, any()}.
+-callback store_last_info(binary(), binary(), non_neg_integer(), binary()) ->
+    {atomic, any()}.
+-callback remove_user(binary(), binary()) -> {atomic, any()}.
 
 start(Host, Opts) ->
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
                              one_queue),
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(last_activity,
-			      [{disc_copies, [node()]},
-			       {attributes,
-				record_info(fields, last_activity)}]),
-	  update_table();
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     gen_iq_handler:add_iq_handler(ejabberd_local, Host,
 				  ?NS_LAST, ?MODULE, process_local_iq, IQDisc),
     gen_iq_handler:add_iq_handler(ejabberd_sm, Host,
@@ -163,38 +161,8 @@ process_sm_iq(From, To,
 %% @spec (LUser::string(), LServer::string()) ->
 %%      {ok, TimeStamp::integer(), Status::string()} | not_found | {error, Reason}
 get_last(LUser, LServer) ->
-    get_last(LUser, LServer,
-	     gen_mod:db_type(LServer, ?MODULE)).
-
-get_last(LUser, LServer, mnesia) ->
-    case catch mnesia:dirty_read(last_activity,
-				 {LUser, LServer})
-	of
-      {'EXIT', Reason} -> {error, Reason};
-      [] -> not_found;
-      [#last_activity{timestamp = TimeStamp,
-		      status = Status}] ->
-	  {ok, TimeStamp, Status}
-    end;
-get_last(LUser, LServer, riak) ->
-    case ejabberd_riak:get(last_activity, last_activity_schema(),
-			   {LUser, LServer}) of
-        {ok, #last_activity{timestamp = TimeStamp,
-                            status = Status}} ->
-            {ok, TimeStamp, Status};
-        {error, notfound} ->
-            not_found;
-        Err ->
-            Err
-    end;
-get_last(LUser, LServer, odbc) ->
-    case catch odbc_queries:get_last(LServer, LUser) of
-        {selected, []} ->
-            not_found;
-        {selected, [{TimeStamp, Status}]} ->
-            {ok, TimeStamp, Status};
-        Reason -> {error, {invalid_result, Reason}}
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_last(LUser, LServer).
 
 get_last_iq(#iq{lang = Lang} = IQ, SubEl, LUser, LServer) ->
     case ejabberd_sm:get_user_resources(LUser, LServer) of
@@ -237,29 +205,8 @@ on_presence_update(User, Server, _Resource, Status) ->
 store_last_info(User, Server, TimeStamp, Status) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    store_last_info(LUser, LServer, TimeStamp, Status,
-		    DBType).
-
-store_last_info(LUser, LServer, TimeStamp, Status,
-		mnesia) ->
-    US = {LUser, LServer},
-    F = fun () ->
-		mnesia:write(#last_activity{us = US,
-					    timestamp = TimeStamp,
-					    status = Status})
-	end,
-    mnesia:transaction(F);
-store_last_info(LUser, LServer, TimeStamp, Status,
-                riak) ->
-    US = {LUser, LServer},
-    {atomic, ejabberd_riak:put(#last_activity{us = US,
-                                              timestamp = TimeStamp,
-                                              status = Status},
-			       last_activity_schema())};
-store_last_info(LUser, LServer, TimeStamp, Status,
-		odbc) ->
-    odbc_queries:set_last_t(LServer, LUser, TimeStamp, Status).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:store_last_info(LUser, LServer, TimeStamp, Status).
 
 %% @spec (LUser::string(), LServer::string()) ->
 %%      {ok, TimeStamp::integer(), Status::string()} | not_found
@@ -272,71 +219,20 @@ get_last_info(LUser, LServer) ->
 remove_user(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    remove_user(LUser, LServer, DBType).
-
-remove_user(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () -> mnesia:delete({last_activity, US}) end,
-    mnesia:transaction(F);
-remove_user(LUser, LServer, odbc) ->
-    odbc_queries:del_last(LServer, LUser);
-remove_user(LUser, LServer, riak) ->
-    {atomic, ejabberd_riak:delete(last_activity, {LUser, LServer})}.
-
-update_table() ->
-    Fields = record_info(fields, last_activity),
-    case mnesia:table_info(last_activity, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            last_activity, Fields, set,
-            fun(#last_activity{us = {U, _}}) -> U end,
-            fun(#last_activity{us = {U, S}, status = Status} = R) ->
-                    R#last_activity{us = {iolist_to_binary(U),
-                                          iolist_to_binary(S)},
-                                    status = iolist_to_binary(Status)}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating last_activity table", []),
-	  mnesia:transform_table(last_activity, ignore, Fields)
-    end.
-
-last_activity_schema() ->
-    {record_info(fields, last_activity), #last_activity{}}.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_user(LUser, LServer).
 
-export(_Server) ->
-    [{last_activity,
-      fun(Host, #last_activity{us = {LUser, LServer},
-                               timestamp = TimeStamp, status = Status})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              Seconds =
-                  ejabberd_odbc:escape(jlib:integer_to_binary(TimeStamp)),
-              State = ejabberd_odbc:escape(Status),
-              [[<<"delete from last where username='">>, Username, <<"';">>],
-               [<<"insert into last(username, seconds, "
-                  "state) values ('">>,
-                Username, <<"', '">>, Seconds, <<"', '">>, State,
-                <<"');">>]];
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select username, seconds, state from last">>,
-      fun([LUser, TimeStamp, State]) ->
-              #last_activity{us = {LUser, LServer},
-                             timestamp = jlib:binary_to_integer(
-                                           TimeStamp),
-                             status = State}
-      end}].
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
 
-import(_LServer, mnesia, #last_activity{} = LA) ->
-    mnesia:dirty_write(LA);
-import(_LServer, riak, #last_activity{} = LA) ->
-    ejabberd_riak:put(LA, last_activity_schema());
-import(_, _, _) ->
-    pass.
+import(LServer, DBType, LA) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, LA).
 
 transform_options(Opts) ->
     lists:foldl(fun transform_options/2, [], Opts).
diff --git a/src/mod_last_mnesia.erl b/src/mod_last_mnesia.erl
new file mode 100644
index 00000000..7a1610ab
--- /dev/null
+++ b/src/mod_last_mnesia.erl
@@ -0,0 +1,72 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_last_mnesia).
+-behaviour(mod_last).
+
+%% API
+-export([init/2, import/2, get_last/2, store_last_info/4, remove_user/2]).
+
+-include("mod_last.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(last_activity,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, last_activity)}]),
+    update_table().
+
+get_last(LUser, LServer) ->
+    case mnesia:dirty_read(last_activity, {LUser, LServer}) of
+	[] ->
+	    not_found;
+	[#last_activity{timestamp = TimeStamp,
+			status = Status}] ->
+	    {ok, TimeStamp, Status}
+    end.
+
+store_last_info(LUser, LServer, TimeStamp, Status) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		mnesia:write(#last_activity{us = US,
+					    timestamp = TimeStamp,
+					    status = Status})
+	end,
+    mnesia:transaction(F).
+
+remove_user(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () -> mnesia:delete({last_activity, US}) end,
+    mnesia:transaction(F).
+
+import(_LServer, #last_activity{} = LA) ->
+    mnesia:dirty_write(LA).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_table() ->
+    Fields = record_info(fields, last_activity),
+    case mnesia:table_info(last_activity, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            last_activity, Fields, set,
+            fun(#last_activity{us = {U, _}}) -> U end,
+            fun(#last_activity{us = {U, S}, status = Status} = R) ->
+                    R#last_activity{us = {iolist_to_binary(U),
+                                          iolist_to_binary(S)},
+                                    status = iolist_to_binary(Status)}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating last_activity table", []),
+	  mnesia:transform_table(last_activity, ignore, Fields)
+    end.
diff --git a/src/mod_last_riak.erl b/src/mod_last_riak.erl
new file mode 100644
index 00000000..d25a3a15
--- /dev/null
+++ b/src/mod_last_riak.erl
@@ -0,0 +1,53 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_last_riak).
+-behaviour(mod_last).
+
+%% API
+-export([init/2, import/2, get_last/2, store_last_info/4, remove_user/2]).
+
+-include("mod_last.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+get_last(LUser, LServer) ->
+    case ejabberd_riak:get(last_activity, last_activity_schema(),
+			   {LUser, LServer}) of
+        {ok, #last_activity{timestamp = TimeStamp,
+                            status = Status}} ->
+            {ok, TimeStamp, Status};
+        {error, notfound} ->
+            not_found;
+        Err ->
+            Err
+    end.
+
+store_last_info(LUser, LServer, TimeStamp, Status) ->
+    US = {LUser, LServer},
+    {atomic, ejabberd_riak:put(#last_activity{us = US,
+                                              timestamp = TimeStamp,
+                                              status = Status},
+			       last_activity_schema())}.
+
+remove_user(LUser, LServer) ->
+    {atomic, ejabberd_riak:delete(last_activity, {LUser, LServer})}.
+
+import(_LServer, #last_activity{} = LA) ->
+    ejabberd_riak:put(LA, last_activity_schema()).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+last_activity_schema() ->
+    {record_info(fields, last_activity), #last_activity{}}.
diff --git a/src/mod_last_sql.erl b/src/mod_last_sql.erl
new file mode 100644
index 00000000..edfa3763
--- /dev/null
+++ b/src/mod_last_sql.erl
@@ -0,0 +1,75 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_last_sql).
+-behaviour(mod_last).
+
+%% API
+-export([init/2, get_last/2, store_last_info/4, remove_user/2,
+	 import/1, import/2, export/1]).
+
+-include("mod_last.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+get_last(LUser, LServer) ->
+    case catch odbc_queries:get_last(LServer, LUser) of
+        {selected, []} ->
+            not_found;
+        {selected, [{TimeStamp, Status}]} ->
+            {ok, TimeStamp, Status};
+        Reason ->
+	    ?ERROR_MSG("failed to get last for user ~s@~s: ~p",
+		       [LUser, LServer, Reason]),
+	    {error, {invalid_result, Reason}}
+    end.
+
+store_last_info(LUser, LServer, TimeStamp, Status) ->
+    odbc_queries:set_last_t(LServer, LUser, TimeStamp, Status).
+
+remove_user(LUser, LServer) ->
+    odbc_queries:del_last(LServer, LUser).
+
+import(_LServer, _LA) ->
+    pass.
+
+export(_Server) ->
+    [{last_activity,
+      fun(Host, #last_activity{us = {LUser, LServer},
+                               timestamp = TimeStamp, status = Status})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              Seconds =
+                  ejabberd_odbc:escape(jlib:integer_to_binary(TimeStamp)),
+              State = ejabberd_odbc:escape(Status),
+              [[<<"delete from last where username='">>, Username, <<"';">>],
+               [<<"insert into last(username, seconds, "
+                  "state) values ('">>,
+                Username, <<"', '">>, Seconds, <<"', '">>, State,
+                <<"');">>]];
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select username, seconds, state from last">>,
+      fun([LUser, TimeStamp, State]) ->
+              #last_activity{us = {LUser, LServer},
+                             timestamp = jlib:binary_to_integer(
+                                           TimeStamp),
+                             status = State}
+      end}].
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_mam.erl b/src/mod_mam.erl
index 862adee9..098ee896 100644
--- a/src/mod_mam.erl
+++ b/src/mod_mam.erl
@@ -35,41 +35,37 @@
 
 -export([user_send_packet/4, user_receive_packet/5,
 	 process_iq_v0_2/3, process_iq_v0_3/3, disco_sm_features/5,
-	 remove_user/2, remove_user/3, mod_opt_type/1, muc_process_iq/4,
+	 remove_user/2, remove_room/3, mod_opt_type/1, muc_process_iq/4,
 	 muc_filter_message/5, message_is_archived/5, delete_old_messages/2,
-	 get_commands_spec/0]).
+	 get_commands_spec/0, msg_to_el/4]).
 
--include_lib("stdlib/include/ms_transform.hrl").
 -include("jlib.hrl").
 -include("logger.hrl").
 -include("mod_muc_room.hrl").
 -include("ejabberd_commands.hrl").
+-include("mod_mam.hrl").
 
 -define(DEF_PAGE_SIZE, 50).
 -define(MAX_PAGE_SIZE, 250).
 
--define(BIN_GREATER_THAN(A, B),
-	((A > B andalso byte_size(A) == byte_size(B))
-	 orelse byte_size(A) > byte_size(B))).
--define(BIN_LESS_THAN(A, B),
-	((A < B andalso byte_size(A) == byte_size(B))
-	 orelse byte_size(A) < byte_size(B))).
-
--record(archive_msg,
-	{us = {<<"">>, <<"">>}                :: {binary(), binary()} | '$2',
-	 id = <<>>                            :: binary() | '_',
-	 timestamp = p1_time_compat:timestamp() :: erlang:timestamp() | '_' | '$1',
-	 peer = {<<"">>, <<"">>, <<"">>}      :: ljid() | '_' | '$3' | undefined,
-	 bare_peer = {<<"">>, <<"">>, <<"">>} :: ljid() | '_' | '$3',
-	 packet = #xmlel{}                    :: xmlel() | '_',
-	 nick = <<"">>                        :: binary(),
-	 type = chat                          :: chat | groupchat}).
-
--record(archive_prefs,
-	{us = {<<"">>, <<"">>} :: {binary(), binary()},
-	 default = never       :: never | always | roster,
-	 always = []           :: [ljid()],
-	 never = []            :: [ljid()]}).
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback remove_user(binary(), binary()) -> any().
+-callback remove_room(binary(), binary(), binary()) -> any().
+-callback delete_old_messages(binary() | global,
+			      erlang:timestamp(),
+			      all | chat | groupchat) -> any().
+-callback extended_fields() -> [xmlel()].
+-callback store(xmlel(), binary(), {binary(), binary()}, chat | groupchat,
+		jid(), binary(), recv | send) -> {ok, binary()} | any().
+-callback write_prefs(binary(), binary(), #archive_prefs{}, binary()) -> ok | any().
+-callback get_prefs(binary(), binary()) -> {ok, #archive_prefs{}} | error.
+-callback select(binary(), jid(), jid(),
+		 none | erlang:timestamp(),
+		 none | erlang:timestamp(),
+		 none | ljid() | {text, binary()},
+		 none | #rsm_in{},
+		 chat | groupchat) ->
+    {[{binary(), non_neg_integer(), xmlel()}], boolean(), non_neg_integer()}.
 
 %%%===================================================================
 %%% API
@@ -77,9 +73,9 @@
 start(Host, Opts) ->
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
 			     one_queue),
-    DBType = gen_mod:db_type(Host, Opts),
-    init_db(DBType, Host),
-    init_cache(DBType, Opts),
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
+    init_cache(Opts),
     gen_iq_handler:add_iq_handler(ejabberd_local, Host,
 				  ?NS_MAM_TMP, ?MODULE, process_iq_v0_2, IQDisc),
     gen_iq_handler:add_iq_handler(ejabberd_sm, Host,
@@ -120,18 +116,7 @@ start(Host, Opts) ->
     ejabberd_commands:register_commands(get_commands_spec()),
     ok.
 
-init_db(mnesia, _Host) ->
-    mnesia:create_table(archive_msg,
-			[{disc_only_copies, [node()]},
-			 {type, bag},
-			 {attributes, record_info(fields, archive_msg)}]),
-    mnesia:create_table(archive_prefs,
-			[{disc_only_copies, [node()]},
-			 {attributes, record_info(fields, archive_prefs)}]);
-init_db(_, _) ->
-    ok.
-
-init_cache(_DBType, Opts) ->
+init_cache(Opts) ->
     MaxSize = gen_mod:get_opt(cache_size, Opts,
 			      fun(I) when is_integer(I), I>0 -> I end,
 			      1000),
@@ -179,24 +164,14 @@ stop(Host) ->
 remove_user(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    remove_user(LUser, LServer,
-		gen_mod:db_type(LServer, ?MODULE)).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_user(LUser, LServer).
 
-remove_user(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () ->
-		mnesia:delete({archive_msg, US}),
-		mnesia:delete({archive_prefs, US})
-	end,
-    mnesia:transaction(F);
-remove_user(LUser, LServer, odbc) ->
-    SUser = ejabberd_odbc:escape(LUser),
-    ejabberd_odbc:sql_query(
-      LServer,
-      [<<"delete from archive where username='">>, SUser, <<"';">>]),
-    ejabberd_odbc:sql_query(
-      LServer,
-      [<<"delete from archive_prefs where username='">>, SUser, <<"';">>]).
+remove_room(LServer, Name, Host) ->
+    LName = jid:nodeprep(Name),
+    LHost = jid:nameprep(Host),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_room(LServer, LName, LHost).
 
 user_receive_packet(Pkt, C2SState, JID, Peer, To) ->
     LUser = JID#jid.luser,
@@ -343,10 +318,10 @@ message_is_archived(false, C2SState, Peer,
 	      if_enabled ->
 		  get_prefs(LUser, LServer);
 	      on_request ->
-		  DBType = gen_mod:db_type(LServer, ?MODULE),
+		  Mod = gen_mod:db_mod(LServer, ?MODULE),
 		  cache_tab:lookup(archive_prefs, {LUser, LServer},
 				   fun() ->
-					   get_prefs(LUser, LServer, DBType)
+					   Mod:get_prefs(LUser, LServer)
 				   end);
 	      never ->
 		  error
@@ -365,21 +340,19 @@ delete_old_messages(TypeBin, Days) when TypeBin == <<"chat">>;
     Diff = Days * 24 * 60 * 60 * 1000000,
     TimeStamp = usec_to_now(p1_time_compat:system_time(micro_seconds) - Diff),
     Type = jlib:binary_to_atom(TypeBin),
-    {Results, _} =
-	lists:foldl(fun(Host, {Results, MnesiaDone}) ->
-			    case {gen_mod:db_type(Host, ?MODULE), MnesiaDone} of
-				{mnesia, true} ->
-				    {Results, true};
-				{mnesia, false} ->
-				    Res = delete_old_messages(TimeStamp, Type,
-							      global, mnesia),
-				    {[Res|Results], true};
-				{DBType, _} ->
-				    Res = delete_old_messages(TimeStamp, Type,
-							      Host, DBType),
-				    {[Res|Results], MnesiaDone}
-			    end
-		    end, {[], false}, ?MYHOSTS),
+    DBTypes = lists:usort(
+		lists:map(
+		  fun(Host) ->
+			  case gen_mod:db_type(Host, ?MODULE) of
+			      odbc -> {odbc, Host};
+			      Other -> {Other, global}
+			  end
+		  end, ?MYHOSTS)),
+    Results = lists:map(
+		fun({DBType, ServerHost}) ->
+			Mod = gen_mod:db_mod(DBType, ?MODULE),
+			Mod:delete_old_messages(ServerHost, TimeStamp, Type)
+		end, DBTypes),
     case lists:filter(fun(Res) -> Res /= ok end, Results) of
 	[] -> ok;
 	[NotOk|_] -> NotOk
@@ -387,21 +360,6 @@ delete_old_messages(TypeBin, Days) when TypeBin == <<"chat">>;
 delete_old_messages(_TypeBin, _Days) ->
     unsupported_type.
 
-delete_old_messages(TimeStamp, Type, global, mnesia) ->
-    MS = ets:fun2ms(fun(#archive_msg{timestamp = MsgTS,
-				     type = MsgType} = Msg)
-			    when MsgTS < TimeStamp,
-				 MsgType == Type orelse Type == all ->
-			    Msg
-		    end),
-    OldMsgs = mnesia:dirty_select(archive_msg, MS),
-    lists:foreach(fun(Rec) ->
-			  ok = mnesia:dirty_delete_object(Rec)
-		  end, OldMsgs);
-delete_old_messages(_TimeStamp, _Type, _Host, _DBType) ->
-    %% TODO
-    not_implemented.
-
 %%%===================================================================
 %%% Internal functions
 %%%===================================================================
@@ -427,15 +385,9 @@ process_iq(LServer, #iq{sub_el = #xmlel{attrs = Attrs}} = IQ) ->
 		    #xmlel{name = <<"field">>,
 			   attrs = [{<<"type">>, <<"text-single">>},
 				    {<<"var">>, <<"end">>}]}],
-    Fields = case gen_mod:db_type(LServer, ?MODULE) of
-		 odbc ->
-		     WithText = #xmlel{name = <<"field">>,
-				       attrs = [{<<"type">>, <<"text-single">>},
-						{<<"var">>, <<"withtext">>}]},
-		     [WithText|CommonFields];
-		 _ ->
-		     CommonFields
-	     end,
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    ExtendedFields = Mod:extended_fields(),
+    Fields = ExtendedFields ++ CommonFields,
     Form = #xmlel{name = <<"x">>,
 		  attrs = [{<<"xmlns">>, ?NS_XDATA}, {<<"type">>, <<"form">>}],
 		  children = Fields},
@@ -715,8 +667,8 @@ store_msg(C2SState, Pkt, LUser, LServer, Peer, Dir) ->
     case should_archive_peer(C2SState, Prefs, Peer) of
 	true ->
 	    US = {LUser, LServer},
-	    store(Pkt, LServer, US, chat, Peer, <<"">>, Dir,
-		  gen_mod:db_type(LServer, ?MODULE));
+	    Mod = gen_mod:db_mod(LServer, ?MODULE),
+	    Mod:store(Pkt, LServer, US, chat, Peer, <<"">>, Dir);
 	false ->
 	    pass
     end.
@@ -726,101 +678,26 @@ store_muc(MUCState, Pkt, RoomJID, Peer, Nick) ->
 	true ->
 	    LServer = MUCState#state.server_host,
 	    {U, S, _} = jid:tolower(RoomJID),
-	    store(Pkt, LServer, {U, S}, groupchat, Peer, Nick, recv,
-		  gen_mod:db_type(LServer, ?MODULE));
+	    Mod = gen_mod:db_mod(LServer, ?MODULE),
+	    Mod:store(Pkt, LServer, {U, S}, groupchat, Peer, Nick, recv);
 	false ->
 	    pass
     end.
 
-store(Pkt, _, {LUser, LServer}, Type, Peer, Nick, _Dir, mnesia) ->
-    LPeer = {PUser, PServer, _} = jid:tolower(Peer),
-    TS = p1_time_compat:timestamp(),
-    ID = jlib:integer_to_binary(now_to_usec(TS)),
-    case mnesia:dirty_write(
-	   #archive_msg{us = {LUser, LServer},
-			id = ID,
-			timestamp = TS,
-			peer = LPeer,
-			bare_peer = {PUser, PServer, <<>>},
-			type = Type,
-			nick = Nick,
-			packet = Pkt}) of
-	ok ->
-	    {ok, ID};
-	Err ->
-	    Err
-    end;
-store(Pkt, LServer, {LUser, LHost}, Type, Peer, Nick, _Dir, odbc) ->
-    TSinteger = p1_time_compat:system_time(micro_seconds),
-    ID = TS = jlib:integer_to_binary(TSinteger),
-    SUser = case Type of
-		chat -> LUser;
-		groupchat -> jid:to_string({LUser, LHost, <<>>})
-	    end,
-    BarePeer = jid:to_string(
-		 jid:tolower(
-		   jid:remove_resource(Peer))),
-    LPeer = jid:to_string(
-	      jid:tolower(Peer)),
-    XML = fxml:element_to_binary(Pkt),
-    Body = fxml:get_subtag_cdata(Pkt, <<"body">>),
-    case ejabberd_odbc:sql_query(
-	    LServer,
-	    [<<"insert into archive (username, timestamp, "
-		    "peer, bare_peer, xml, txt, kind, nick) values (">>,
-		<<"'">>, ejabberd_odbc:escape(SUser), <<"', ">>,
-		<<"'">>, TS, <<"', ">>,
-		<<"'">>, ejabberd_odbc:escape(LPeer), <<"', ">>,
-		<<"'">>, ejabberd_odbc:escape(BarePeer), <<"', ">>,
-		<<"'">>, ejabberd_odbc:escape(XML), <<"', ">>,
-		<<"'">>, ejabberd_odbc:escape(Body), <<"', ">>,
-		<<"'">>, jlib:atom_to_binary(Type), <<"', ">>,
-		<<"'">>, ejabberd_odbc:escape(Nick), <<"');">>]) of
-	{updated, _} ->
-	    {ok, ID};
-	Err ->
-	    Err
-    end.
-
 write_prefs(LUser, LServer, Host, Default, Always, Never) ->
-    DBType = case gen_mod:db_type(Host, ?MODULE) of
-		 odbc -> {odbc, Host};
-		 DB -> DB
-	     end,
     Prefs = #archive_prefs{us = {LUser, LServer},
 			   default = Default,
 			   always = Always,
 			   never = Never},
+    Mod = gen_mod:db_mod(Host, ?MODULE),
     cache_tab:dirty_insert(
       archive_prefs, {LUser, LServer}, Prefs,
-      fun() ->  write_prefs(LUser, LServer, Prefs, DBType) end).
-
-write_prefs(_LUser, _LServer, Prefs, mnesia) ->
-    mnesia:dirty_write(Prefs);
-write_prefs(LUser, _LServer, #archive_prefs{default = Default,
-					   never = Never,
-					   always = Always},
-	    {odbc, Host}) ->
-    SUser = ejabberd_odbc:escape(LUser),
-    SDefault = erlang:atom_to_binary(Default, utf8),
-    SAlways = ejabberd_odbc:encode_term(Always),
-    SNever = ejabberd_odbc:encode_term(Never),
-    case update(Host, <<"archive_prefs">>,
-		[<<"username">>, <<"def">>, <<"always">>, <<"never">>],
-		[SUser, SDefault, SAlways, SNever],
-		[<<"username='">>, SUser, <<"'">>]) of
-	{updated, _} ->
-	    ok;
-	Err ->
-	    Err
-    end.
+      fun() ->  Mod:write_prefs(LUser, LServer, Prefs, Host) end).
 
 get_prefs(LUser, LServer) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
     Res = cache_tab:lookup(archive_prefs, {LUser, LServer},
-			   fun() -> get_prefs(LUser, LServer,
-					      DBType)
-			   end),
+			   fun() -> Mod:get_prefs(LUser, LServer) end),
     case Res of
 	{ok, Prefs} ->
 	    Prefs;
@@ -842,31 +719,6 @@ get_prefs(LUser, LServer) ->
 	    end
     end.
 
-get_prefs(LUser, LServer, mnesia) ->
-    case mnesia:dirty_read(archive_prefs, {LUser, LServer}) of
-	[Prefs] ->
-	    {ok, Prefs};
-	_ ->
-	    error
-    end;
-get_prefs(LUser, LServer, odbc) ->
-    case ejabberd_odbc:sql_query(
-	   LServer,
-	   [<<"select def, always, never from archive_prefs ">>,
-	    <<"where username='">>,
-	    ejabberd_odbc:escape(LUser), <<"';">>]) of
-	{selected, _, [[SDefault, SAlways, SNever]]} ->
-	    Default = erlang:binary_to_existing_atom(SDefault, utf8),
-	    Always = ejabberd_odbc:decode_term(SAlways),
-	    Never = ejabberd_odbc:decode_term(SNever),
-	    {ok, #archive_prefs{us = {LUser, LServer},
-		    default = Default,
-		    always = Always,
-		    never = Never}};
-	_ ->
-	    error
-    end.
-
 prefs_el(Default, Always, Never, NS) ->
     Default1 = jlib:atom_to_binary(Default),
     JFun = fun(L) ->
@@ -890,11 +742,10 @@ maybe_activate_mam(LUser, LServer) ->
 					 false),
     case ActivateOpt of
 	true ->
+	    Mod = gen_mod:db_mod(LServer, ?MODULE),
 	    Res = cache_tab:lookup(archive_prefs, {LUser, LServer},
 				   fun() ->
-					   get_prefs(LUser, LServer,
-						     gen_mod:db_type(LServer,
-								     ?MODULE))
+					   Mod:get_prefs(LUser, LServer)
 				   end),
 	    case Res of
 		{ok, _Prefs} ->
@@ -912,31 +763,22 @@ maybe_activate_mam(LUser, LServer) ->
     end.
 
 select_and_send(LServer, From, To, Start, End, With, RSM, IQ, MsgType) ->
-    DBType = case gen_mod:db_type(LServer, ?MODULE) of
-		 odbc -> {odbc, LServer};
-		 DB -> DB
-	     end,
-    select_and_send(LServer, From, To, Start, End, With, RSM, IQ,
-		    MsgType, DBType).
-
-select_and_send(LServer, From, To, Start, End, With, RSM, IQ, MsgType, DBType) ->
     {Msgs, IsComplete, Count} = select_and_start(LServer, From, To, Start, End,
-						 With, RSM, MsgType, DBType),
+						 With, RSM, MsgType),
     SortedMsgs = lists:keysort(2, Msgs),
     send(From, To, SortedMsgs, RSM, Count, IsComplete, IQ).
 
-select_and_start(LServer, From, To, Start, End, With, RSM, MsgType, DBType) ->
+select_and_start(LServer, From, To, Start, End, With, RSM, MsgType) ->
     case MsgType of
 	chat ->
-	    select(LServer, From, From, Start, End, With, RSM, MsgType, DBType);
+	    select(LServer, From, From, Start, End, With, RSM, MsgType);
 	{groupchat, _Role, _MUCState} ->
-	    select(LServer, From, To, Start, End, With, RSM, MsgType, DBType)
+	    select(LServer, From, To, Start, End, With, RSM, MsgType)
     end.
 
 select(_LServer, JidRequestor, JidArchive, Start, End, _With, RSM,
        {groupchat, _Role, #state{config = #config{mam = false},
-				 history = History}} = MsgType,
-       _DBType) ->
+				 history = History}} = MsgType) ->
     #lqueue{len = L, queue = Q} = History,
     {Msgs0, _} =
 	lists:mapfoldl(
@@ -970,81 +812,9 @@ select(_LServer, JidRequestor, JidArchive, Start, End, _With, RSM,
 	_ ->
 	    {Msgs, true, L}
     end;
-select(_LServer, JidRequestor,
-       #jid{luser = LUser, lserver = LServer} = JidArchive,
-       Start, End, With, RSM, MsgType, mnesia) ->
-    MS = make_matchspec(LUser, LServer, Start, End, With),
-    Msgs = mnesia:dirty_select(archive_msg, MS),
-    SortedMsgs = lists:keysort(#archive_msg.timestamp, Msgs),
-    {FilteredMsgs, IsComplete} = filter_by_rsm(SortedMsgs, RSM),
-    Count = length(Msgs),
-    {lists:map(
-       fun(Msg) ->
-	       {Msg#archive_msg.id,
-		jlib:binary_to_integer(Msg#archive_msg.id),
-		msg_to_el(Msg, MsgType, JidRequestor, JidArchive)}
-       end, FilteredMsgs), IsComplete, Count};
-select(LServer, JidRequestor, #jid{luser = LUser} = JidArchive,
-       Start, End, With, RSM, MsgType, {odbc, Host}) ->
-    User = case MsgType of
-	       chat -> LUser;
-	       {groupchat, _Role, _MUCState} -> jid:to_string(JidArchive)
-	   end,
-    {Query, CountQuery} = make_sql_query(User, LServer,
-					 Start, End, With, RSM),
-    % TODO from XEP-0313 v0.2: "To conserve resources, a server MAY place a
-    % reasonable limit on how many stanzas may be pushed to a client in one
-    % request. If a query returns a number of stanzas greater than this limit
-    % and the client did not specify a limit using RSM then the server should
-    % return a policy-violation error to the client." We currently don't do this
-    % for v0.2 requests, but we do limit #rsm_in.max for v0.3 and newer.
-    case {ejabberd_odbc:sql_query(Host, Query),
-	  ejabberd_odbc:sql_query(Host, CountQuery)} of
-	{{selected, _, Res}, {selected, _, [[Count]]}} ->
-	    {Max, Direction} = case RSM of
-				   #rsm_in{max = M, direction = D} -> {M, D};
-				   _ -> {undefined, undefined}
-			       end,
-	    {Res1, IsComplete} =
-		if Max >= 0 andalso Max /= undefined andalso length(Res) > Max ->
-			if Direction == before ->
-				{lists:nthtail(1, Res), false};
-			   true ->
-				{lists:sublist(Res, Max), false}
-			end;
-		   true ->
-			{Res, true}
-		end,
-	    {lists:flatmap(
-	       fun([TS, XML, PeerBin, Kind, Nick]) ->
-		       try
-			   #xmlel{} = El = fxml_stream:parse_element(XML),
-			   Now = usec_to_now(jlib:binary_to_integer(TS)),
-			   PeerJid = jid:tolower(jid:from_string(PeerBin)),
-			   T = case Kind of
-				   <<"">> -> chat;
-				   null -> chat;
-				   _ -> jlib:binary_to_atom(Kind)
-			       end,
-			   [{TS, jlib:binary_to_integer(TS),
-			     msg_to_el(#archive_msg{timestamp = Now,
-						    packet = El,
-						    type = T,
-						    nick = Nick,
-						    peer = PeerJid},
-				       MsgType, JidRequestor, JidArchive)}]
-		       catch _:Err ->
-			       ?ERROR_MSG("failed to parse data from SQL: ~p. "
-					  "The data was: "
-					  "timestamp = ~s, xml = ~s, "
-					  "peer = ~s, kind = ~s, nick = ~s",
-					  [Err, TS, XML, PeerBin, Kind, Nick]),
-			       []
-		       end
-	       end, Res1), IsComplete, jlib:binary_to_integer(Count)};
-	_ ->
-	    {[], false, 0}
-    end.
+select(LServer, From, From, Start, End, With, RSM, MsgType) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:select(LServer, From, From, Start, End, With, RSM, MsgType).
 
 msg_to_el(#archive_msg{timestamp = TS, packet = Pkt1, nick = Nick, peer = Peer},
 	  MsgType, JidRequestor, #jid{lserver = LServer} = JidArchive) ->
@@ -1160,7 +930,6 @@ send(From, To, Msgs, RSM, Count, IsComplete, #iq{sub_el = SubEl} = IQ) ->
 	    ignore
     end.
 
-
 make_rsm_out([], _, Count, Attrs, NS) ->
     Tag = if NS == ?NS_MAM_TMP -> <<"query">>;
 	     true -> <<"fin">>
@@ -1177,32 +946,6 @@ make_rsm_out([{FirstID, _, _}|_] = Msgs, _, Count, Attrs, NS) ->
 			 #rsm_out{first = FirstID, count = Count,
 				  last = LastID})}].
 
-filter_by_rsm(Msgs, none) ->
-    {Msgs, true};
-filter_by_rsm(_Msgs, #rsm_in{max = Max}) when Max < 0 ->
-    {[], true};
-filter_by_rsm(Msgs, #rsm_in{max = Max, direction = Direction, id = ID}) ->
-    NewMsgs = case Direction of
-		  aft when ID /= <<"">> ->
-		      lists:filter(
-			fun(#archive_msg{id = I}) ->
-				?BIN_GREATER_THAN(I, ID)
-			end, Msgs);
-		  before when ID /= <<"">> ->
-		      lists:foldl(
-			fun(#archive_msg{id = I} = Msg, Acc)
-				when ?BIN_LESS_THAN(I, ID) ->
-				[Msg|Acc];
-			   (_, Acc) ->
-				Acc
-			end, [], Msgs);
-		  before when ID == <<"">> ->
-		      lists:reverse(Msgs);
-		  _ ->
-		      Msgs
-	      end,
-    filter_by_max(NewMsgs, Max).
-
 filter_by_max(Msgs, undefined) ->
     {Msgs, true};
 filter_by_max(Msgs, Len) when is_integer(Len), Len >= 0 ->
@@ -1231,126 +974,6 @@ match_rsm(Now, #rsm_in{id = ID, direction = before}) when ID /= <<"">> ->
 match_rsm(_Now, _) ->
     true.
 
-make_matchspec(LUser, LServer, Start, End, {_, _, <<>>} = With) ->
-    ets:fun2ms(
-      fun(#archive_msg{timestamp = TS,
-		       us = US,
-		       bare_peer = BPeer} = Msg)
-	    when Start =< TS, End >= TS,
-		 US == {LUser, LServer},
-		 BPeer == With ->
-	      Msg
-      end);
-make_matchspec(LUser, LServer, Start, End, {_, _, _} = With) ->
-    ets:fun2ms(
-      fun(#archive_msg{timestamp = TS,
-		       us = US,
-		       peer = Peer} = Msg)
-	    when Start =< TS, End >= TS,
-		 US == {LUser, LServer},
-		 Peer == With ->
-	      Msg
-      end);
-make_matchspec(LUser, LServer, Start, End, none) ->
-    ets:fun2ms(
-      fun(#archive_msg{timestamp = TS,
-		       us = US,
-		       peer = Peer} = Msg)
-	    when Start =< TS, End >= TS,
-		 US == {LUser, LServer} ->
-	      Msg
-      end).
-
-make_sql_query(User, LServer, Start, End, With, RSM) ->
-    {Max, Direction, ID} = case RSM of
-	#rsm_in{} ->
-	    {RSM#rsm_in.max,
-		RSM#rsm_in.direction,
-		RSM#rsm_in.id};
-	none ->
-	    {none, none, <<>>}
-    end,
-    ODBCType = ejabberd_config:get_option(
-		 {odbc_type, LServer},
-		 ejabberd_odbc:opt_type(odbc_type)),
-    LimitClause = if is_integer(Max), Max >= 0, ODBCType /= mssql ->
-			  [<<" limit ">>, jlib:integer_to_binary(Max+1)];
-		     true ->
-			  []
-		  end,
-    TopClause = if is_integer(Max), Max >= 0, ODBCType == mssql ->
-			  [<<" TOP ">>, jlib:integer_to_binary(Max+1)];
-		     true ->
-			  []
-		  end,
-    WithClause = case With of
-		     {text, <<>>} ->
-			 [];
-		     {text, Txt} ->
-			 [<<" and match (txt) against ('">>,
-			  ejabberd_odbc:escape(Txt), <<"')">>];
-		     {_, _, <<>>} ->
-			 [<<" and bare_peer='">>,
-			  ejabberd_odbc:escape(jid:to_string(With)),
-			  <<"'">>];
-		     {_, _, _} ->
-			 [<<" and peer='">>,
-			  ejabberd_odbc:escape(jid:to_string(With)),
-			  <<"'">>];
-		     none ->
-			 []
-		 end,
-    PageClause = case catch jlib:binary_to_integer(ID) of
-		     I when is_integer(I), I >= 0 ->
-			 case Direction of
-			     before ->
-				 [<<" AND timestamp < ">>, ID];
-			     aft ->
-				 [<<" AND timestamp > ">>, ID];
-			     _ ->
-				 []
-			 end;
-		     _ ->
-			 []
-		 end,
-    StartClause = case Start of
-		      {_, _, _} ->
-			  [<<" and timestamp >= ">>,
-			   jlib:integer_to_binary(now_to_usec(Start))];
-		      _ ->
-			  []
-		  end,
-    EndClause = case End of
-		    {_, _, _} ->
-			[<<" and timestamp <= ">>,
-			 jlib:integer_to_binary(now_to_usec(End))];
-		    _ ->
-			[]
-		end,
-    SUser = ejabberd_odbc:escape(User),
-
-    Query = [<<"SELECT ">>, TopClause, <<" timestamp, xml, peer, kind, nick"
-	      " FROM archive WHERE username='">>,
-	     SUser, <<"'">>, WithClause, StartClause, EndClause,
-	     PageClause],
-
-    QueryPage =
-	case Direction of
-	    before ->
-		% ID can be empty because of
-		% XEP-0059: Result Set Management
-		% 2.5 Requesting the Last Page in a Result Set
-		[<<"SELECT timestamp, xml, peer, kind, nick FROM (">>, Query,
-		 <<" ORDER BY timestamp DESC ">>,
-		 LimitClause, <<") AS t ORDER BY timestamp ASC;">>];
-	    _ ->
-		[Query, <<" ORDER BY timestamp ASC ">>,
-		 LimitClause, <<";">>]
-	end,
-    {QueryPage,
-     [<<"SELECT COUNT(*) FROM archive WHERE username='">>,
-      SUser, <<"'">>, WithClause, StartClause, EndClause, <<";">>]}.
-
 now_to_usec({MSec, Sec, USec}) ->
     (MSec*1000000 + Sec)*1000000 + USec.
 
@@ -1376,28 +999,6 @@ get_jids(Els) ->
 	      []
       end, Els).
 
-update(LServer, Table, Fields, Vals, Where) ->
-    UPairs = lists:zipwith(fun (A, B) ->
-				   <<A/binary, "='", B/binary, "'">>
-			   end,
-			   Fields, Vals),
-    case ejabberd_odbc:sql_query(LServer,
-				 [<<"update ">>, Table, <<" set ">>,
-				  join(UPairs, <<", ">>), <<" where ">>, Where,
-				  <<";">>])
-	of
-	{updated, 1} -> {updated, 1};
-	_ ->
-	    ejabberd_odbc:sql_query(LServer,
-				    [<<"insert into ">>, Table, <<"(">>,
-				     join(Fields, <<", ">>), <<") values ('">>,
-				     join(Vals, <<"', '">>), <<"');">>])
-    end.
-
-%% Almost a copy of string:join/2.
-join([], _Sep) -> [];
-join([H | T], Sep) -> [H, [[Sep, X] || X <- T]].
-
 get_commands_spec() ->
     [#ejabberd_commands{name = delete_old_mam_messages, tags = [purge],
 			desc = "Delete MAM messages older than DAYS",
@@ -1416,7 +1017,11 @@ mod_opt_type(cache_life_time) ->
     fun (I) when is_integer(I), I > 0 -> I end;
 mod_opt_type(cache_size) ->
     fun (I) when is_integer(I), I > 0 -> I end;
-mod_opt_type(db_type) -> fun gen_mod:v_db/1;
+mod_opt_type(db_type) ->
+    fun(odbc) -> odbc;
+       (internal) -> mnesia;
+       (mnesia) -> mnesia
+    end;
 mod_opt_type(default) ->
     fun (always) -> always;
 	(never) -> never;
diff --git a/src/mod_mam_mnesia.erl b/src/mod_mam_mnesia.erl
new file mode 100644
index 00000000..007ef5eb
--- /dev/null
+++ b/src/mod_mam_mnesia.erl
@@ -0,0 +1,178 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 15 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_mam_mnesia).
+
+-behaviour(mod_mam).
+
+%% API
+-export([init/2, remove_user/2, remove_room/3, delete_old_messages/3,
+	 extended_fields/0, store/7, write_prefs/4, get_prefs/2, select/8]).
+
+-include_lib("stdlib/include/ms_transform.hrl").
+-include("jlib.hrl").
+-include("mod_mam.hrl").
+
+-define(BIN_GREATER_THAN(A, B),
+	((A > B andalso byte_size(A) == byte_size(B))
+	 orelse byte_size(A) > byte_size(B))).
+-define(BIN_LESS_THAN(A, B),
+	((A < B andalso byte_size(A) == byte_size(B))
+	 orelse byte_size(A) < byte_size(B))).
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(archive_msg,
+			[{disc_only_copies, [node()]},
+			 {type, bag},
+			 {attributes, record_info(fields, archive_msg)}]),
+    mnesia:create_table(archive_prefs,
+			[{disc_only_copies, [node()]},
+			 {attributes, record_info(fields, archive_prefs)}]).
+
+remove_user(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		mnesia:delete({archive_msg, US}),
+		mnesia:delete({archive_prefs, US})
+	end,
+    mnesia:transaction(F).
+
+remove_room(_LServer, LName, LHost) ->
+    remove_user(LName, LHost).
+
+delete_old_messages(global, TimeStamp, Type) ->
+    MS = ets:fun2ms(fun(#archive_msg{timestamp = MsgTS,
+				     type = MsgType} = Msg)
+			  when MsgTS < TimeStamp,
+			       MsgType == Type orelse Type == all ->
+			    Msg
+		    end),
+    OldMsgs = mnesia:dirty_select(archive_msg, MS),
+    lists:foreach(fun(Rec) ->
+			  ok = mnesia:dirty_delete_object(Rec)
+		  end, OldMsgs).
+
+extended_fields() ->
+    [].
+
+store(Pkt, _, {LUser, LServer}, Type, Peer, Nick, _Dir) ->
+    LPeer = {PUser, PServer, _} = jid:tolower(Peer),
+    TS = p1_time_compat:timestamp(),
+    ID = jlib:integer_to_binary(now_to_usec(TS)),
+    case mnesia:dirty_write(
+	   #archive_msg{us = {LUser, LServer},
+			id = ID,
+			timestamp = TS,
+			peer = LPeer,
+			bare_peer = {PUser, PServer, <<>>},
+			type = Type,
+			nick = Nick,
+			packet = Pkt}) of
+	ok ->
+	    {ok, ID};
+	Err ->
+	    Err
+    end.
+
+write_prefs(_LUser, _LServer, Prefs, _ServerHost) ->
+    mnesia:dirty_write(Prefs).
+
+get_prefs(LUser, LServer) ->
+    case mnesia:dirty_read(archive_prefs, {LUser, LServer}) of
+	[Prefs] ->
+	    {ok, Prefs};
+	_ ->
+	    error
+    end.
+
+select(_LServer, JidRequestor,
+       #jid{luser = LUser, lserver = LServer} = JidArchive,
+       Start, End, With, RSM, MsgType) ->
+    MS = make_matchspec(LUser, LServer, Start, End, With),
+    Msgs = mnesia:dirty_select(archive_msg, MS),
+    SortedMsgs = lists:keysort(#archive_msg.timestamp, Msgs),
+    {FilteredMsgs, IsComplete} = filter_by_rsm(SortedMsgs, RSM),
+    Count = length(Msgs),
+    {lists:map(
+       fun(Msg) ->
+	       {Msg#archive_msg.id,
+		jlib:binary_to_integer(Msg#archive_msg.id),
+		mod_mam:msg_to_el(Msg, MsgType, JidRequestor, JidArchive)}
+       end, FilteredMsgs), IsComplete, Count}.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+now_to_usec({MSec, Sec, USec}) ->
+    (MSec*1000000 + Sec)*1000000 + USec.
+
+make_matchspec(LUser, LServer, Start, End, {_, _, <<>>} = With) ->
+    ets:fun2ms(
+      fun(#archive_msg{timestamp = TS,
+		       us = US,
+		       bare_peer = BPeer} = Msg)
+	    when Start =< TS, End >= TS,
+		 US == {LUser, LServer},
+		 BPeer == With ->
+	      Msg
+      end);
+make_matchspec(LUser, LServer, Start, End, {_, _, _} = With) ->
+    ets:fun2ms(
+      fun(#archive_msg{timestamp = TS,
+		       us = US,
+		       peer = Peer} = Msg)
+	    when Start =< TS, End >= TS,
+		 US == {LUser, LServer},
+		 Peer == With ->
+	      Msg
+      end);
+make_matchspec(LUser, LServer, Start, End, none) ->
+    ets:fun2ms(
+      fun(#archive_msg{timestamp = TS,
+		       us = US,
+		       peer = Peer} = Msg)
+	    when Start =< TS, End >= TS,
+		 US == {LUser, LServer} ->
+	      Msg
+      end).
+
+filter_by_rsm(Msgs, none) ->
+    {Msgs, true};
+filter_by_rsm(_Msgs, #rsm_in{max = Max}) when Max < 0 ->
+    {[], true};
+filter_by_rsm(Msgs, #rsm_in{max = Max, direction = Direction, id = ID}) ->
+    NewMsgs = case Direction of
+		  aft when ID /= <<"">> ->
+		      lists:filter(
+			fun(#archive_msg{id = I}) ->
+				?BIN_GREATER_THAN(I, ID)
+			end, Msgs);
+		  before when ID /= <<"">> ->
+		      lists:foldl(
+			fun(#archive_msg{id = I} = Msg, Acc)
+				when ?BIN_LESS_THAN(I, ID) ->
+				[Msg|Acc];
+			   (_, Acc) ->
+				Acc
+			end, [], Msgs);
+		  before when ID == <<"">> ->
+		      lists:reverse(Msgs);
+		  _ ->
+		      Msgs
+	      end,
+    filter_by_max(NewMsgs, Max).
+
+filter_by_max(Msgs, undefined) ->
+    {Msgs, true};
+filter_by_max(Msgs, Len) when is_integer(Len), Len >= 0 ->
+    {lists:sublist(Msgs, Len), length(Msgs) =< Len};
+filter_by_max(_Msgs, _Junk) ->
+    {[], true}.
diff --git a/src/mod_mam_sql.erl b/src/mod_mam_sql.erl
new file mode 100644
index 00000000..1f24de31
--- /dev/null
+++ b/src/mod_mam_sql.erl
@@ -0,0 +1,309 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 15 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_mam_sql).
+
+-behaviour(mod_mam).
+
+%% API
+-export([init/2, remove_user/2, remove_room/3, delete_old_messages/3,
+	 extended_fields/0, store/7, write_prefs/4, get_prefs/2, select/8]).
+
+-include_lib("stdlib/include/ms_transform.hrl").
+-include("jlib.hrl").
+-include("mod_mam.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+remove_user(LUser, LServer) ->
+    SUser = ejabberd_odbc:escape(LUser),
+    ejabberd_odbc:sql_query(
+      LServer,
+      [<<"delete from archive where username='">>, SUser, <<"';">>]),
+    ejabberd_odbc:sql_query(
+      LServer,
+      [<<"delete from archive_prefs where username='">>, SUser, <<"';">>]).
+
+remove_room(LServer, LName, LHost) ->
+    LUser = jid:to_string({LName, LHost, <<>>}),
+    remove_user(LUser, LServer).
+
+delete_old_messages(ServerHost, TimeStamp, Type) ->
+    TypeClause = if Type == all -> <<"">>;
+		    true -> [<<" and kind='">>, jlib:atom_to_binary(Type), <<"'">>]
+		 end,
+    TS = integer_to_binary(now_to_usec(TimeStamp)),
+    ejabberd_odbc:sql_query(
+      ServerHost, [<<"delete from archive where timestamp<">>,
+		   TS, TypeClause, <<";">>]),
+    ok.
+
+extended_fields() ->
+    [#xmlel{name = <<"field">>,
+	    attrs = [{<<"type">>, <<"text-single">>},
+		     {<<"var">>, <<"withtext">>}]}].
+
+store(Pkt, LServer, {LUser, LHost}, Type, Peer, Nick, _Dir) ->
+    TSinteger = p1_time_compat:system_time(micro_seconds),
+    ID = TS = jlib:integer_to_binary(TSinteger),
+    SUser = case Type of
+		chat -> LUser;
+		groupchat -> jid:to_string({LUser, LHost, <<>>})
+	    end,
+    BarePeer = jid:to_string(
+		 jid:tolower(
+		   jid:remove_resource(Peer))),
+    LPeer = jid:to_string(
+	      jid:tolower(Peer)),
+    XML = fxml:element_to_binary(Pkt),
+    Body = fxml:get_subtag_cdata(Pkt, <<"body">>),
+    case ejabberd_odbc:sql_query(
+	    LServer,
+	    [<<"insert into archive (username, timestamp, "
+		    "peer, bare_peer, xml, txt, kind, nick) values (">>,
+		<<"'">>, ejabberd_odbc:escape(SUser), <<"', ">>,
+		<<"'">>, TS, <<"', ">>,
+		<<"'">>, ejabberd_odbc:escape(LPeer), <<"', ">>,
+		<<"'">>, ejabberd_odbc:escape(BarePeer), <<"', ">>,
+		<<"'">>, ejabberd_odbc:escape(XML), <<"', ">>,
+		<<"'">>, ejabberd_odbc:escape(Body), <<"', ">>,
+		<<"'">>, jlib:atom_to_binary(Type), <<"', ">>,
+		<<"'">>, ejabberd_odbc:escape(Nick), <<"');">>]) of
+	{updated, _} ->
+	    {ok, ID};
+	Err ->
+	    Err
+    end.
+
+write_prefs(LUser, _LServer, #archive_prefs{default = Default,
+					   never = Never,
+					   always = Always},
+	    ServerHost) ->
+    SUser = ejabberd_odbc:escape(LUser),
+    SDefault = erlang:atom_to_binary(Default, utf8),
+    SAlways = ejabberd_odbc:encode_term(Always),
+    SNever = ejabberd_odbc:encode_term(Never),
+    case update(ServerHost, <<"archive_prefs">>,
+		[<<"username">>, <<"def">>, <<"always">>, <<"never">>],
+		[SUser, SDefault, SAlways, SNever],
+		[<<"username='">>, SUser, <<"'">>]) of
+	{updated, _} ->
+	    ok;
+	Err ->
+	    Err
+    end.
+
+get_prefs(LUser, LServer) ->
+    case ejabberd_odbc:sql_query(
+	   LServer,
+	   [<<"select def, always, never from archive_prefs ">>,
+	    <<"where username='">>,
+	    ejabberd_odbc:escape(LUser), <<"';">>]) of
+	{selected, _, [[SDefault, SAlways, SNever]]} ->
+	    Default = erlang:binary_to_existing_atom(SDefault, utf8),
+	    Always = ejabberd_odbc:decode_term(SAlways),
+	    Never = ejabberd_odbc:decode_term(SNever),
+	    {ok, #archive_prefs{us = {LUser, LServer},
+		    default = Default,
+		    always = Always,
+		    never = Never}};
+	_ ->
+	    error
+    end.
+
+select(LServer, JidRequestor, #jid{luser = LUser} = JidArchive,
+       Start, End, With, RSM, MsgType) ->
+    User = case MsgType of
+	       chat -> LUser;
+	       {groupchat, _Role, _MUCState} -> jid:to_string(JidArchive)
+	   end,
+    {Query, CountQuery} = make_sql_query(User, LServer,
+					 Start, End, With, RSM),
+    % TODO from XEP-0313 v0.2: "To conserve resources, a server MAY place a
+    % reasonable limit on how many stanzas may be pushed to a client in one
+    % request. If a query returns a number of stanzas greater than this limit
+    % and the client did not specify a limit using RSM then the server should
+    % return a policy-violation error to the client." We currently don't do this
+    % for v0.2 requests, but we do limit #rsm_in.max for v0.3 and newer.
+    case {ejabberd_odbc:sql_query(LServer, Query),
+	  ejabberd_odbc:sql_query(LServer, CountQuery)} of
+	{{selected, _, Res}, {selected, _, [[Count]]}} ->
+	    {Max, Direction} = case RSM of
+				   #rsm_in{max = M, direction = D} -> {M, D};
+				   _ -> {undefined, undefined}
+			       end,
+	    {Res1, IsComplete} =
+		if Max >= 0 andalso Max /= undefined andalso length(Res) > Max ->
+			if Direction == before ->
+				{lists:nthtail(1, Res), false};
+			   true ->
+				{lists:sublist(Res, Max), false}
+			end;
+		   true ->
+			{Res, true}
+		end,
+	    {lists:flatmap(
+	       fun([TS, XML, PeerBin, Kind, Nick]) ->
+		       try
+			   #xmlel{} = El = fxml_stream:parse_element(XML),
+			   Now = usec_to_now(jlib:binary_to_integer(TS)),
+			   PeerJid = jid:tolower(jid:from_string(PeerBin)),
+			   T = case Kind of
+				   <<"">> -> chat;
+				   null -> chat;
+				   _ -> jlib:binary_to_atom(Kind)
+			       end,
+			   [{TS, jlib:binary_to_integer(TS),
+			     mod_mam:msg_to_el(#archive_msg{timestamp = Now,
+							    packet = El,
+							    type = T,
+							    nick = Nick,
+							    peer = PeerJid},
+					       MsgType, JidRequestor, JidArchive)}]
+		       catch _:Err ->
+			       ?ERROR_MSG("failed to parse data from SQL: ~p. "
+					  "The data was: "
+					  "timestamp = ~s, xml = ~s, "
+					  "peer = ~s, kind = ~s, nick = ~s",
+					  [Err, TS, XML, PeerBin, Kind, Nick]),
+			       []
+		       end
+	       end, Res1), IsComplete, jlib:binary_to_integer(Count)};
+	_ ->
+	    {[], false, 0}
+    end.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+now_to_usec({MSec, Sec, USec}) ->
+    (MSec*1000000 + Sec)*1000000 + USec.
+
+usec_to_now(Int) ->
+    Secs = Int div 1000000,
+    USec = Int rem 1000000,
+    MSec = Secs div 1000000,
+    Sec = Secs rem 1000000,
+    {MSec, Sec, USec}.
+
+make_sql_query(User, LServer, Start, End, With, RSM) ->
+    {Max, Direction, ID} = case RSM of
+	#rsm_in{} ->
+	    {RSM#rsm_in.max,
+		RSM#rsm_in.direction,
+		RSM#rsm_in.id};
+	none ->
+	    {none, none, <<>>}
+    end,
+    ODBCType = ejabberd_config:get_option(
+		 {odbc_type, LServer},
+		 ejabberd_odbc:opt_type(odbc_type)),
+    LimitClause = if is_integer(Max), Max >= 0, ODBCType /= mssql ->
+			  [<<" limit ">>, jlib:integer_to_binary(Max+1)];
+		     true ->
+			  []
+		  end,
+    TopClause = if is_integer(Max), Max >= 0, ODBCType == mssql ->
+			  [<<" TOP ">>, jlib:integer_to_binary(Max+1)];
+		     true ->
+			  []
+		  end,
+    WithClause = case With of
+		     {text, <<>>} ->
+			 [];
+		     {text, Txt} ->
+			 [<<" and match (txt) against ('">>,
+			  ejabberd_odbc:escape(Txt), <<"')">>];
+		     {_, _, <<>>} ->
+			 [<<" and bare_peer='">>,
+			  ejabberd_odbc:escape(jid:to_string(With)),
+			  <<"'">>];
+		     {_, _, _} ->
+			 [<<" and peer='">>,
+			  ejabberd_odbc:escape(jid:to_string(With)),
+			  <<"'">>];
+		     none ->
+			 []
+		 end,
+    PageClause = case catch jlib:binary_to_integer(ID) of
+		     I when is_integer(I), I >= 0 ->
+			 case Direction of
+			     before ->
+				 [<<" AND timestamp < ">>, ID];
+			     aft ->
+				 [<<" AND timestamp > ">>, ID];
+			     _ ->
+				 []
+			 end;
+		     _ ->
+			 []
+		 end,
+    StartClause = case Start of
+		      {_, _, _} ->
+			  [<<" and timestamp >= ">>,
+			   jlib:integer_to_binary(now_to_usec(Start))];
+		      _ ->
+			  []
+		  end,
+    EndClause = case End of
+		    {_, _, _} ->
+			[<<" and timestamp <= ">>,
+			 jlib:integer_to_binary(now_to_usec(End))];
+		    _ ->
+			[]
+		end,
+    SUser = ejabberd_odbc:escape(User),
+
+    Query = [<<"SELECT ">>, TopClause, <<" timestamp, xml, peer, kind, nick"
+	      " FROM archive WHERE username='">>,
+	     SUser, <<"'">>, WithClause, StartClause, EndClause,
+	     PageClause],
+
+    QueryPage =
+	case Direction of
+	    before ->
+		% ID can be empty because of
+		% XEP-0059: Result Set Management
+		% 2.5 Requesting the Last Page in a Result Set
+		[<<"SELECT timestamp, xml, peer, kind, nick FROM (">>, Query,
+		 <<" ORDER BY timestamp DESC ">>,
+		 LimitClause, <<") AS t ORDER BY timestamp ASC;">>];
+	    _ ->
+		[Query, <<" ORDER BY timestamp ASC ">>,
+		 LimitClause, <<";">>]
+	end,
+    {QueryPage,
+     [<<"SELECT COUNT(*) FROM archive WHERE username='">>,
+      SUser, <<"'">>, WithClause, StartClause, EndClause, <<";">>]}.
+
+update(LServer, Table, Fields, Vals, Where) ->
+    UPairs = lists:zipwith(fun (A, B) ->
+				   <<A/binary, "='", B/binary, "'">>
+			   end,
+			   Fields, Vals),
+    case ejabberd_odbc:sql_query(LServer,
+				 [<<"update ">>, Table, <<" set ">>,
+				  join(UPairs, <<", ">>), <<" where ">>, Where,
+				  <<";">>])
+	of
+	{updated, 1} -> {updated, 1};
+	_ ->
+	    ejabberd_odbc:sql_query(LServer,
+				    [<<"insert into ">>, Table, <<"(">>,
+				     join(Fields, <<", ">>), <<") values ('">>,
+				     join(Vals, <<"', '">>), <<"');">>])
+    end.
+
+%% Almost a copy of string:join/2.
+join([], _Sep) -> [];
+join([H | T], Sep) -> [H, [[Sep, X] || X <- T]].
diff --git a/src/mod_muc.erl b/src/mod_muc.erl
index 9d4b4985..6aa18631 100644
--- a/src/mod_muc.erl
+++ b/src/mod_muc.erl
@@ -48,6 +48,7 @@
 	 export/1,
 	 import/1,
 	 import/3,
+	 opts_to_binary/1,
 	 can_use_nick/4]).
 
 -export([init/1, handle_call/3, handle_cast/2,
@@ -72,6 +73,17 @@
 
 -define(MAX_ROOMS_DISCOITEMS, 100).
 
+-type muc_room_opts() :: [{atom(), any()}].
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #muc_room{} | #muc_registered{}) -> ok | pass.
+-callback store_room(binary(), binary(), binary(), list()) -> {atomic, any()}.
+-callback restore_room(binary(), binary(), binary()) -> muc_room_opts() | error.
+-callback forget_room(binary(), binary(), binary()) -> {atomic, any()}.
+-callback can_use_nick(binary(), binary(), jid(), binary()) -> boolean().
+-callback get_rooms(binary(), binary()) -> [#muc_room{}].
+-callback get_nick(binary(), binary(), jid()) -> binary() | error.
+-callback set_nick(binary(), binary(), jid(), binary()) -> {atomic, ok | false}.
+
 %%====================================================================
 %% API
 %%====================================================================
@@ -125,96 +137,24 @@ create_room(Host, Name, From, Nick, Opts) ->
 
 store_room(ServerHost, Host, Name, Opts) ->
     LServer = jid:nameprep(ServerHost),
-    store_room(LServer, Host, Name, Opts,
-	       gen_mod:db_type(LServer, ?MODULE)).
-
-store_room(_LServer, Host, Name, Opts, mnesia) ->
-    F = fun () ->
-		mnesia:write(#muc_room{name_host = {Name, Host},
-				       opts = Opts})
-	end,
-    mnesia:transaction(F);
-store_room(_LServer, Host, Name, Opts, riak) ->
-    {atomic, ejabberd_riak:put(#muc_room{name_host = {Name, Host},
-                                         opts = Opts},
-			       muc_room_schema())};
-store_room(LServer, Host, Name, Opts, odbc) ->
-    SName = ejabberd_odbc:escape(Name),
-    SHost = ejabberd_odbc:escape(Host),
-    SOpts = ejabberd_odbc:encode_term(Opts),
-    F = fun () ->
-		odbc_queries:update_t(<<"muc_room">>,
-				      [<<"name">>, <<"host">>, <<"opts">>],
-				      [SName, SHost, SOpts],
-				      [<<"name='">>, SName, <<"' and host='">>,
-				       SHost, <<"'">>])
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:store_room(LServer, Host, Name, Opts).
 
 restore_room(ServerHost, Host, Name) ->
     LServer = jid:nameprep(ServerHost),
-    restore_room(LServer, Host, Name,
-                 gen_mod:db_type(LServer, ?MODULE)).
-
-restore_room(_LServer, Host, Name, mnesia) ->
-    case catch mnesia:dirty_read(muc_room, {Name, Host}) of
-      [#muc_room{opts = Opts}] -> Opts;
-      _ -> error
-    end;
-restore_room(_LServer, Host, Name, riak) ->
-    case ejabberd_riak:get(muc_room, muc_room_schema(), {Name, Host}) of
-        {ok, #muc_room{opts = Opts}} -> Opts;
-        _ -> error
-    end;
-restore_room(LServer, Host, Name, odbc) ->
-    SName = ejabberd_odbc:escape(Name),
-    SHost = ejabberd_odbc:escape(Host),
-    case catch ejabberd_odbc:sql_query(LServer,
-				       [<<"select opts from muc_room where name='">>,
-					SName, <<"' and host='">>, SHost,
-					<<"';">>])
-	of
-      {selected, [<<"opts">>], [[Opts]]} ->
-	  opts_to_binary(ejabberd_odbc:decode_term(Opts));
-      _ -> error
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:restore_room(LServer, Host, Name).
 
 forget_room(ServerHost, Host, Name) ->
     LServer = jid:nameprep(ServerHost),
-    forget_room(LServer, Host, Name,
-		gen_mod:db_type(LServer, ?MODULE)).
-
-forget_room(LServer, Host, Name, mnesia) ->
-    remove_room_mam(LServer, Host, Name),
-    F = fun () -> mnesia:delete({muc_room, {Name, Host}})
-	end,
-    mnesia:transaction(F);
-forget_room(LServer, Host, Name, riak) ->
     remove_room_mam(LServer, Host, Name),
-    {atomic, ejabberd_riak:delete(muc_room, {Name, Host})};
-forget_room(LServer, Host, Name, odbc) ->
-    remove_room_mam(LServer, Host, Name),
-    SName = ejabberd_odbc:escape(Name),
-    SHost = ejabberd_odbc:escape(Host),
-    F = fun () ->
-		ejabberd_odbc:sql_query_t([<<"delete from muc_room where name='">>,
-					   SName, <<"' and host='">>, SHost,
-					   <<"';">>])
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:forget_room(LServer, Host, Name).
 
 remove_room_mam(LServer, Host, Name) ->
     case gen_mod:is_loaded(LServer, mod_mam) of
 	true ->
-	    U = jid:nodeprep(Name),
-	    S = jid:nameprep(Host),
-	    DBType = gen_mod:db_type(LServer, mod_mam),
-	    if DBType == odbc ->
-		    mod_mam:remove_user(jid:to_string({U, S, <<>>}),
-					LServer, DBType);
-	       true ->
-		    mod_mam:remove_user(U, S, DBType)
-	    end;
+	    mod_mam:remove_room(LServer, Name, Host);
 	false ->
 	    ok
     end.
@@ -233,48 +173,8 @@ process_iq_disco_items(Host, From, To,
 can_use_nick(_ServerHost, _Host, _JID, <<"">>) -> false;
 can_use_nick(ServerHost, Host, JID, Nick) ->
     LServer = jid:nameprep(ServerHost),
-    can_use_nick(LServer, Host, JID, Nick,
-		 gen_mod:db_type(LServer, ?MODULE)).
-
-can_use_nick(_LServer, Host, JID, Nick, mnesia) ->
-    {LUser, LServer, _} = jid:tolower(JID),
-    LUS = {LUser, LServer},
-    case catch mnesia:dirty_select(muc_registered,
-				   [{#muc_registered{us_host = '$1',
-						     nick = Nick, _ = '_'},
-				     [{'==', {element, 2, '$1'}, Host}],
-				     ['$_']}])
-	of
-      {'EXIT', _Reason} -> true;
-      [] -> true;
-      [#muc_registered{us_host = {U, _Host}}] -> U == LUS
-    end;
-can_use_nick(LServer, Host, JID, Nick, riak) ->
-    {LUser, LServer, _} = jid:tolower(JID),
-    LUS = {LUser, LServer},
-    case ejabberd_riak:get_by_index(muc_registered,
-				    muc_registered_schema(),
-                                    <<"nick_host">>, {Nick, Host}) of
-        {ok, []} ->
-            true;
-        {ok, [#muc_registered{us_host = {U, _Host}}]} ->
-            U == LUS;
-        {error, _} ->
-            true
-    end;
-can_use_nick(LServer, Host, JID, Nick, odbc) ->
-    SJID =
-	jid:to_string(jid:tolower(jid:remove_resource(JID))),
-    SNick = ejabberd_odbc:escape(Nick),
-    SHost = ejabberd_odbc:escape(Host),
-    case catch ejabberd_odbc:sql_query(LServer,
-				       [<<"select jid from muc_registered ">>,
-					<<"where nick='">>, SNick,
-					<<"' and host='">>, SHost, <<"';">>])
-	of
-      {selected, [<<"jid">>], [[SJID1]]} -> SJID == SJID1;
-      _ -> true
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:can_use_nick(LServer, Host, JID, Nick).
 
 %%====================================================================
 %% gen_server callbacks
@@ -283,21 +183,8 @@ can_use_nick(LServer, Host, JID, Nick, odbc) ->
 init([Host, Opts]) ->
     MyHost = gen_mod:get_opt_host(Host, Opts,
 				  <<"conference.@HOST@">>),
-    case gen_mod:db_type(Host, Opts) of
-        mnesia ->
-            mnesia:create_table(muc_room,
-                                [{disc_copies, [node()]},
-                                 {attributes,
-                                  record_info(fields, muc_room)}]),
-            mnesia:create_table(muc_registered,
-                                [{disc_copies, [node()]},
-                                 {attributes,
-                                  record_info(fields, muc_registered)}]),
-            update_tables(MyHost),
-            mnesia:add_table_index(muc_registered, nick);
-        _ ->
-            ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, [{host, MyHost}|Opts]),
     mnesia:create_table(muc_online_room,
 			[{ram_copies, [node()]},
 			 {attributes, record_info(fields, muc_online_room)}]),
@@ -647,43 +534,8 @@ check_create_roomid(ServerHost, RoomID) ->
 
 get_rooms(ServerHost, Host) ->
     LServer = jid:nameprep(ServerHost),
-    get_rooms(LServer, Host,
-              gen_mod:db_type(LServer, ?MODULE)).
-
-get_rooms(_LServer, Host, mnesia) ->
-    case catch mnesia:dirty_select(muc_room,
-				   [{#muc_room{name_host = {'_', Host},
-					       _ = '_'},
-				     [], ['$_']}])
-	of
-      {'EXIT', Reason} -> ?ERROR_MSG("~p", [Reason]), [];
-      Rs -> Rs
-    end;
-get_rooms(_LServer, Host, riak) ->
-    case ejabberd_riak:get(muc_room, muc_room_schema()) of
-        {ok, Rs} ->
-            lists:filter(
-              fun(#muc_room{name_host = {_, H}}) ->
-                      Host == H
-              end, Rs);
-        _Err ->
-            []
-    end;
-get_rooms(LServer, Host, odbc) ->
-    SHost = ejabberd_odbc:escape(Host),
-    case catch ejabberd_odbc:sql_query(LServer,
-				       [<<"select name, opts from muc_room ">>,
-					<<"where host='">>, SHost, <<"';">>])
-	of
-      {selected, [<<"name">>, <<"opts">>], RoomOpts} ->
-	  lists:map(fun ([Room, Opts]) ->
-			    #muc_room{name_host = {Room, Host},
-				      opts = opts_to_binary(
-                                               ejabberd_odbc:decode_term(Opts))}
-		    end,
-		    RoomOpts);
-      Err -> ?ERROR_MSG("failed to get rooms: ~p", [Err]), []
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_rooms(LServer, Host).
 
 load_permanent_rooms(Host, ServerHost, Access,
 		     HistorySize, RoomShaper) ->
@@ -873,41 +725,8 @@ iq_get_unique(From) ->
 
 get_nick(ServerHost, Host, From) ->
     LServer = jid:nameprep(ServerHost),
-    get_nick(LServer, Host, From,
-	     gen_mod:db_type(LServer, ?MODULE)).
-
-get_nick(_LServer, Host, From, mnesia) ->
-    {LUser, LServer, _} = jid:tolower(From),
-    LUS = {LUser, LServer},
-    case catch mnesia:dirty_read(muc_registered,
-				 {LUS, Host})
-	of
-      {'EXIT', _Reason} -> error;
-      [] -> error;
-      [#muc_registered{nick = Nick}] -> Nick
-    end;
-get_nick(LServer, Host, From, riak) ->
-    {LUser, LServer, _} = jid:tolower(From),
-    US = {LUser, LServer},
-    case ejabberd_riak:get(muc_registered,
-			   muc_registered_schema(),
-			   {US, Host}) of
-        {ok, #muc_registered{nick = Nick}} -> Nick;
-        {error, _} -> error
-    end;
-get_nick(LServer, Host, From, odbc) ->
-    SJID =
-	ejabberd_odbc:escape(jid:to_string(jid:tolower(jid:remove_resource(From)))),
-    SHost = ejabberd_odbc:escape(Host),
-    case catch ejabberd_odbc:sql_query(LServer,
-				       [<<"select nick from muc_registered where "
-					  "jid='">>,
-					SJID, <<"' and host='">>, SHost,
-					<<"';">>])
-	of
-      {selected, [<<"nick">>], [[Nick]]} -> Nick;
-      _ -> error
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_nick(LServer, Host, From).
 
 iq_get_register_info(ServerHost, Host, From, Lang) ->
     {Nick, Registered} = case get_nick(ServerHost, Host,
@@ -946,107 +765,8 @@ iq_get_register_info(ServerHost, Host, From, Lang) ->
 
 set_nick(ServerHost, Host, From, Nick) ->
     LServer = jid:nameprep(ServerHost),
-    set_nick(LServer, Host, From, Nick,
-	     gen_mod:db_type(LServer, ?MODULE)).
-
-set_nick(_LServer, Host, From, Nick, mnesia) ->
-    {LUser, LServer, _} = jid:tolower(From),
-    LUS = {LUser, LServer},
-    F = fun () ->
-		case Nick of
-		  <<"">> ->
-		      mnesia:delete({muc_registered, {LUS, Host}}), ok;
-		  _ ->
-		      Allow = case mnesia:select(muc_registered,
-						 [{#muc_registered{us_host =
-								       '$1',
-								   nick = Nick,
-								   _ = '_'},
-						   [{'==', {element, 2, '$1'},
-						     Host}],
-						   ['$_']}])
-				  of
-				[] -> true;
-				[#muc_registered{us_host = {U, _Host}}] ->
-				    U == LUS
-			      end,
-		      if Allow ->
-			     mnesia:write(#muc_registered{us_host = {LUS, Host},
-							  nick = Nick}),
-			     ok;
-			 true -> false
-		      end
-		end
-	end,
-    mnesia:transaction(F);
-set_nick(LServer, Host, From, Nick, riak) ->
-    {LUser, LServer, _} = jid:tolower(From),
-    LUS = {LUser, LServer},
-    {atomic,
-     case Nick of
-         <<"">> ->
-             ejabberd_riak:delete(muc_registered, {LUS, Host});
-         _ ->
-             Allow = case ejabberd_riak:get_by_index(
-                            muc_registered,
-			    muc_registered_schema(),
-                            <<"nick_host">>, {Nick, Host}) of
-                         {ok, []} ->
-                             true;
-                         {ok, [#muc_registered{us_host = {U, _Host}}]} ->
-                             U == LUS;
-                         {error, _} ->
-                             false
-                     end,
-             if Allow ->
-                     ejabberd_riak:put(#muc_registered{us_host = {LUS, Host},
-                                                       nick = Nick},
-				       muc_registered_schema(),
-                                       [{'2i', [{<<"nick_host">>,
-                                                 {Nick, Host}}]}]);
-                true ->
-                     false
-             end
-     end};
-set_nick(LServer, Host, From, Nick, odbc) ->
-    JID =
-	jid:to_string(jid:tolower(jid:remove_resource(From))),
-    SJID = ejabberd_odbc:escape(JID),
-    SNick = ejabberd_odbc:escape(Nick),
-    SHost = ejabberd_odbc:escape(Host),
-    F = fun () ->
-		case Nick of
-		  <<"">> ->
-		      ejabberd_odbc:sql_query_t([<<"delete from muc_registered where ">>,
-						 <<"jid='">>, SJID,
-						 <<"' and host='">>, Host,
-						 <<"';">>]),
-		      ok;
-		  _ ->
-		      Allow = case
-				ejabberd_odbc:sql_query_t([<<"select jid from muc_registered ">>,
-							   <<"where nick='">>,
-							   SNick,
-							   <<"' and host='">>,
-							   SHost, <<"';">>])
-				  of
-				{selected, [<<"jid">>], [[J]]} -> J == JID;
-				_ -> true
-			      end,
-		      if Allow ->
-			     odbc_queries:update_t(<<"muc_registered">>,
-						   [<<"jid">>, <<"host">>,
-						    <<"nick">>],
-						   [SJID, SHost, SNick],
-						   [<<"jid='">>, SJID,
-						    <<"' and host='">>, SHost,
-						    <<"'">>]),
-			     ok;
-			 true -> false
-		      end
-		end
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:set_nick(LServer, Host, From, Nick).
 
 iq_set_register_info(ServerHost, Host, From, Nick,
 		     Lang) ->
@@ -1192,118 +912,17 @@ opts_to_binary(Opts) ->
               Opt
       end, Opts).
 
-update_tables(Host) ->
-    update_muc_room_table(Host),
-    update_muc_registered_table(Host).
-
-muc_room_schema() ->
-    {record_info(fields, muc_room), #muc_room{}}.
-
-muc_registered_schema() ->
-    {record_info(fields, muc_registered), #muc_registered{}}.
-
-update_muc_room_table(_Host) ->
-    Fields = record_info(fields, muc_room),
-    case mnesia:table_info(muc_room, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            muc_room, Fields, set,
-            fun(#muc_room{name_host = {N, _}}) -> N end,
-            fun(#muc_room{name_host = {N, H},
-                          opts = Opts} = R) ->
-                    R#muc_room{name_host = {iolist_to_binary(N),
-                                            iolist_to_binary(H)},
-                               opts = opts_to_binary(Opts)}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating muc_room table", []),
-	  mnesia:transform_table(muc_room, ignore, Fields)
-    end.
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
-update_muc_registered_table(_Host) ->
-    Fields = record_info(fields, muc_registered),
-    case mnesia:table_info(muc_registered, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            muc_registered, Fields, set,
-            fun(#muc_registered{us_host = {_, H}}) -> H end,
-            fun(#muc_registered{us_host = {{U, S}, H},
-                                nick = Nick} = R) ->
-                    R#muc_registered{us_host = {{iolist_to_binary(U),
-                                                 iolist_to_binary(S)},
-                                                iolist_to_binary(H)},
-                                     nick = iolist_to_binary(Nick)}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating muc_registered table", []),
-	  mnesia:transform_table(muc_registered, ignore, Fields)
-    end.
+import(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
 
-export(_Server) ->
-    [{muc_room,
-      fun(Host, #muc_room{name_host = {Name, RoomHost}, opts = Opts}) ->
-              case str:suffix(Host, RoomHost) of
-                  true ->
-                      SName = ejabberd_odbc:escape(Name),
-                      SRoomHost = ejabberd_odbc:escape(RoomHost),
-                      SOpts = ejabberd_odbc:encode_term(Opts),
-                      [[<<"delete from muc_room where name='">>, SName,
-                        <<"' and host='">>, SRoomHost, <<"';">>],
-                       [<<"insert into muc_room(name, host, opts) ",
-                          "values (">>,
-                        <<"'">>, SName, <<"', '">>, SRoomHost,
-                        <<"', '">>, SOpts, <<"');">>]];
-                  false ->
-                      []
-              end
-      end},
-     {muc_registered,
-      fun(Host, #muc_registered{us_host = {{U, S}, RoomHost},
-                                nick = Nick}) ->
-              case str:suffix(Host, RoomHost) of
-                  true ->
-                      SJID = ejabberd_odbc:escape(
-                               jid:to_string(
-                                 jid:make(U, S, <<"">>))),
-                      SNick = ejabberd_odbc:escape(Nick),
-                      SRoomHost = ejabberd_odbc:escape(RoomHost),
-                      [[<<"delete from muc_registered where jid='">>,
-                        SJID, <<"' and host='">>, SRoomHost, <<"';">>],
-                       [<<"insert into muc_registered(jid, host, "
-                          "nick) values ('">>,
-                        SJID, <<"', '">>, SRoomHost, <<"', '">>, SNick,
-                        <<"');">>]];
-                  false ->
-                      []
-              end
-      end}].
-
-import(_LServer) ->
-    [{<<"select name, host, opts from muc_room;">>,
-      fun([Name, RoomHost, SOpts]) ->
-              Opts = opts_to_binary(ejabberd_odbc:decode_term(SOpts)),
-              #muc_room{name_host = {Name, RoomHost}, opts = Opts}
-      end},
-     {<<"select jid, host, nick from muc_registered;">>,
-      fun([J, RoomHost, Nick]) ->
-              #jid{user = U, server = S} =
-                  jid:from_string(J),
-              #muc_registered{us_host = {{U, S}, RoomHost},
-                              nick = Nick}
-      end}].
-
-import(_LServer, mnesia, #muc_room{} = R) ->
-    mnesia:dirty_write(R);
-import(_LServer, mnesia, #muc_registered{} = R) ->
-    mnesia:dirty_write(R);
-import(_LServer, riak, #muc_room{} = R) ->
-    ejabberd_riak:put(R, muc_room_schema());
-import(_LServer, riak,
-       #muc_registered{us_host = {_, Host}, nick = Nick} = R) ->
-    ejabberd_riak:put(R, muc_registered_schema(),
-		      [{'2i', [{<<"nick_host">>, {Nick, Host}}]}]);
-import(_, _, _) ->
-    pass.
+import(LServer, DBType, Data) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, Data).
 
 mod_opt_type(access) ->
     fun (A) when is_atom(A) -> A end;
diff --git a/src/mod_muc_mnesia.erl b/src/mod_muc_mnesia.erl
new file mode 100644
index 00000000..e3ae3697
--- /dev/null
+++ b/src/mod_muc_mnesia.erl
@@ -0,0 +1,163 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_muc_mnesia).
+
+-behaviour(mod_muc).
+
+%% API
+-export([init/2, import/2, store_room/4, restore_room/3, forget_room/3,
+	 can_use_nick/4, get_rooms/2, get_nick/3, set_nick/4]).
+
+-include("mod_muc.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, Opts) ->
+    MyHost = proplists:get_value(host, Opts),
+    mnesia:create_table(muc_room,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, muc_room)}]),
+    mnesia:create_table(muc_registered,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, muc_registered)}]),
+    update_tables(MyHost),
+    mnesia:add_table_index(muc_registered, nick).
+
+store_room(_LServer, Host, Name, Opts) ->
+    F = fun () ->
+		mnesia:write(#muc_room{name_host = {Name, Host},
+				       opts = Opts})
+	end,
+    mnesia:transaction(F).
+
+restore_room(_LServer, Host, Name) ->
+    case catch mnesia:dirty_read(muc_room, {Name, Host}) of
+	[#muc_room{opts = Opts}] -> Opts;
+	_ -> error
+    end.
+
+forget_room(_LServer, Host, Name) ->
+    F = fun () -> mnesia:delete({muc_room, {Name, Host}})
+	end,
+    mnesia:transaction(F).
+
+can_use_nick(_LServer, Host, JID, Nick) ->
+    {LUser, LServer, _} = jid:tolower(JID),
+    LUS = {LUser, LServer},
+    case catch mnesia:dirty_select(muc_registered,
+				   [{#muc_registered{us_host = '$1',
+						     nick = Nick, _ = '_'},
+				     [{'==', {element, 2, '$1'}, Host}],
+				     ['$_']}])
+	of
+      {'EXIT', _Reason} -> true;
+      [] -> true;
+      [#muc_registered{us_host = {U, _Host}}] -> U == LUS
+    end.
+
+get_rooms(_LServer, Host) ->
+    mnesia:dirty_select(muc_room,
+			[{#muc_room{name_host = {'_', Host},
+				    _ = '_'},
+			  [], ['$_']}]).
+
+get_nick(_LServer, Host, From) ->
+    {LUser, LServer, _} = jid:tolower(From),
+    LUS = {LUser, LServer},
+    case mnesia:dirty_read(muc_registered, {LUS, Host}) of
+	[] -> error;
+	[#muc_registered{nick = Nick}] -> Nick
+    end.
+
+set_nick(_LServer, Host, From, Nick) ->
+    {LUser, LServer, _} = jid:tolower(From),
+    LUS = {LUser, LServer},
+    F = fun () ->
+		case Nick of
+		    <<"">> ->
+			mnesia:delete({muc_registered, {LUS, Host}}),
+			ok;
+		    _ ->
+			Allow = case mnesia:select(
+				       muc_registered,
+				       [{#muc_registered{us_host =
+							     '$1',
+							 nick = Nick,
+							 _ = '_'},
+					 [{'==', {element, 2, '$1'},
+					   Host}],
+					 ['$_']}]) of
+				    [] -> true;
+				    [#muc_registered{us_host = {U, _Host}}] ->
+					U == LUS
+				end,
+			if Allow ->
+				mnesia:write(#muc_registered{
+						us_host = {LUS, Host},
+						nick = Nick}),
+				ok;
+			   true ->
+				false
+			end
+		end
+	end,
+    mnesia:transaction(F).
+
+import(_LServer, #muc_room{} = R) ->
+    mnesia:dirty_write(R);
+import(_LServer, #muc_registered{} = R) ->
+    mnesia:dirty_write(R).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_tables(Host) ->
+    update_muc_room_table(Host),
+    update_muc_registered_table(Host).
+
+update_muc_room_table(_Host) ->
+    Fields = record_info(fields, muc_room),
+    case mnesia:table_info(muc_room, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            muc_room, Fields, set,
+            fun(#muc_room{name_host = {N, _}}) -> N end,
+            fun(#muc_room{name_host = {N, H},
+                          opts = Opts} = R) ->
+                    R#muc_room{name_host = {iolist_to_binary(N),
+                                            iolist_to_binary(H)},
+                               opts = mod_muc:opts_to_binary(Opts)}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating muc_room table", []),
+	  mnesia:transform_table(muc_room, ignore, Fields)
+    end.
+
+update_muc_registered_table(_Host) ->
+    Fields = record_info(fields, muc_registered),
+    case mnesia:table_info(muc_registered, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            muc_registered, Fields, set,
+            fun(#muc_registered{us_host = {_, H}}) -> H end,
+            fun(#muc_registered{us_host = {{U, S}, H},
+                                nick = Nick} = R) ->
+                    R#muc_registered{us_host = {{iolist_to_binary(U),
+                                                 iolist_to_binary(S)},
+                                                iolist_to_binary(H)},
+                                     nick = iolist_to_binary(Nick)}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating muc_registered table", []),
+	  mnesia:transform_table(muc_registered, ignore, Fields)
+    end.
diff --git a/src/mod_muc_riak.erl b/src/mod_muc_riak.erl
new file mode 100644
index 00000000..bc6e5959
--- /dev/null
+++ b/src/mod_muc_riak.erl
@@ -0,0 +1,117 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_muc_riak).
+
+-behaviour(mod_muc).
+
+%% API
+-export([init/2, import/2, store_room/4, restore_room/3, forget_room/3,
+	 can_use_nick/4, get_rooms/2, get_nick/3, set_nick/4]).
+
+-include("mod_muc.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+store_room(_LServer, Host, Name, Opts) ->
+    {atomic, ejabberd_riak:put(#muc_room{name_host = {Name, Host},
+                                         opts = Opts},
+			       muc_room_schema())}.
+
+restore_room(_LServer, Host, Name) ->
+    case ejabberd_riak:get(muc_room, muc_room_schema(), {Name, Host}) of
+        {ok, #muc_room{opts = Opts}} -> Opts;
+        _ -> error
+    end.
+
+forget_room(_LServer, Host, Name) ->
+    {atomic, ejabberd_riak:delete(muc_room, {Name, Host})}.
+
+can_use_nick(LServer, Host, JID, Nick) ->
+    {LUser, LServer, _} = jid:tolower(JID),
+    LUS = {LUser, LServer},
+    case ejabberd_riak:get_by_index(muc_registered,
+				    muc_registered_schema(),
+                                    <<"nick_host">>, {Nick, Host}) of
+        {ok, []} ->
+            true;
+        {ok, [#muc_registered{us_host = {U, _Host}}]} ->
+            U == LUS;
+        {error, _} ->
+            true
+    end.
+
+get_rooms(_LServer, Host) ->
+    case ejabberd_riak:get(muc_room, muc_room_schema()) of
+        {ok, Rs} ->
+            lists:filter(
+              fun(#muc_room{name_host = {_, H}}) ->
+                      Host == H
+              end, Rs);
+        _Err ->
+            []
+    end.
+
+get_nick(LServer, Host, From) ->
+    {LUser, LServer, _} = jid:tolower(From),
+    US = {LUser, LServer},
+    case ejabberd_riak:get(muc_registered,
+			   muc_registered_schema(),
+			   {US, Host}) of
+        {ok, #muc_registered{nick = Nick}} -> Nick;
+        {error, _} -> error
+    end.
+
+set_nick(LServer, Host, From, Nick) ->
+    {LUser, LServer, _} = jid:tolower(From),
+    LUS = {LUser, LServer},
+    {atomic,
+     case Nick of
+         <<"">> ->
+             ejabberd_riak:delete(muc_registered, {LUS, Host});
+         _ ->
+             Allow = case ejabberd_riak:get_by_index(
+                            muc_registered,
+			    muc_registered_schema(),
+                            <<"nick_host">>, {Nick, Host}) of
+                         {ok, []} ->
+                             true;
+                         {ok, [#muc_registered{us_host = {U, _Host}}]} ->
+                             U == LUS;
+                         {error, _} ->
+                             false
+                     end,
+             if Allow ->
+                     ejabberd_riak:put(#muc_registered{us_host = {LUS, Host},
+                                                       nick = Nick},
+				       muc_registered_schema(),
+                                       [{'2i', [{<<"nick_host">>,
+                                                 {Nick, Host}}]}]);
+                true ->
+                     false
+             end
+     end}.
+
+import(_LServer, #muc_room{} = R) ->
+    ejabberd_riak:put(R, muc_room_schema());
+import(_LServer, #muc_registered{us_host = {_, Host}, nick = Nick} = R) ->
+    ejabberd_riak:put(R, muc_registered_schema(),
+		      [{'2i', [{<<"nick_host">>, {Nick, Host}}]}]).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+muc_room_schema() ->
+    {record_info(fields, muc_room), #muc_room{}}.
+
+muc_registered_schema() ->
+    {record_info(fields, muc_registered), #muc_registered{}}.
diff --git a/src/mod_muc_sql.erl b/src/mod_muc_sql.erl
new file mode 100644
index 00000000..9acd9f8d
--- /dev/null
+++ b/src/mod_muc_sql.erl
@@ -0,0 +1,202 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_muc_sql).
+
+-behaviour(mod_muc).
+
+%% API
+-export([init/2, store_room/4, restore_room/3, forget_room/3,
+	 can_use_nick/4, get_rooms/2, get_nick/3, set_nick/4,
+	 import/1, import/2, export/1]).
+
+-include("jlib.hrl").
+-include("mod_muc.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+store_room(LServer, Host, Name, Opts) ->
+    SName = ejabberd_odbc:escape(Name),
+    SHost = ejabberd_odbc:escape(Host),
+    SOpts = ejabberd_odbc:encode_term(Opts),
+    F = fun () ->
+		odbc_queries:update_t(<<"muc_room">>,
+				      [<<"name">>, <<"host">>, <<"opts">>],
+				      [SName, SHost, SOpts],
+				      [<<"name='">>, SName, <<"' and host='">>,
+				       SHost, <<"'">>])
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+restore_room(LServer, Host, Name) ->
+    SName = ejabberd_odbc:escape(Name),
+    SHost = ejabberd_odbc:escape(Host),
+    case catch ejabberd_odbc:sql_query(LServer,
+				       [<<"select opts from muc_room where name='">>,
+					SName, <<"' and host='">>, SHost,
+					<<"';">>]) of
+	{selected, [<<"opts">>], [[Opts]]} ->
+	    mod_muc:opts_to_binary(ejabberd_odbc:decode_term(Opts));
+	_ ->
+	    error
+    end.
+
+forget_room(LServer, Host, Name) ->
+    SName = ejabberd_odbc:escape(Name),
+    SHost = ejabberd_odbc:escape(Host),
+    F = fun () ->
+		ejabberd_odbc:sql_query_t([<<"delete from muc_room where name='">>,
+					   SName, <<"' and host='">>, SHost,
+					   <<"';">>])
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+can_use_nick(LServer, Host, JID, Nick) ->
+    SJID = jid:to_string(jid:tolower(jid:remove_resource(JID))),
+    SNick = ejabberd_odbc:escape(Nick),
+    SHost = ejabberd_odbc:escape(Host),
+    case catch ejabberd_odbc:sql_query(LServer,
+				       [<<"select jid from muc_registered ">>,
+					<<"where nick='">>, SNick,
+					<<"' and host='">>, SHost, <<"';">>]) of
+	{selected, [<<"jid">>], [[SJID1]]} -> SJID == SJID1;
+	_ -> true
+    end.
+
+get_rooms(LServer, Host) ->
+    SHost = ejabberd_odbc:escape(Host),
+    case catch ejabberd_odbc:sql_query(LServer,
+				       [<<"select name, opts from muc_room ">>,
+					<<"where host='">>, SHost, <<"';">>]) of
+	{selected, [<<"name">>, <<"opts">>], RoomOpts} ->
+	    lists:map(
+	      fun([Room, Opts]) ->
+		      #muc_room{name_host = {Room, Host},
+				opts = mod_muc:opts_to_binary(
+					 ejabberd_odbc:decode_term(Opts))}
+	      end, RoomOpts);
+	Err ->
+	    ?ERROR_MSG("failed to get rooms: ~p", [Err]),
+	    []
+    end.
+
+get_nick(LServer, Host, From) ->
+    SJID = ejabberd_odbc:escape(jid:to_string(jid:tolower(jid:remove_resource(From)))),
+    SHost = ejabberd_odbc:escape(Host),
+    case catch ejabberd_odbc:sql_query(LServer,
+				       [<<"select nick from muc_registered where "
+					  "jid='">>,
+					SJID, <<"' and host='">>, SHost,
+					<<"';">>]) of
+	{selected, [<<"nick">>], [[Nick]]} -> Nick;
+	_ -> error
+    end.
+
+set_nick(LServer, Host, From, Nick) ->
+    JID = jid:to_string(jid:tolower(jid:remove_resource(From))),
+    SJID = ejabberd_odbc:escape(JID),
+    SNick = ejabberd_odbc:escape(Nick),
+    SHost = ejabberd_odbc:escape(Host),
+    F = fun () ->
+		case Nick of
+		    <<"">> ->
+			ejabberd_odbc:sql_query_t(
+			  [<<"delete from muc_registered where ">>,
+			   <<"jid='">>, SJID,
+			   <<"' and host='">>, Host,
+			   <<"';">>]),
+			ok;
+		    _ ->
+			Allow = case ejabberd_odbc:sql_query_t(
+				       [<<"select jid from muc_registered ">>,
+					<<"where nick='">>,
+					SNick,
+					<<"' and host='">>,
+					SHost, <<"';">>]) of
+				    {selected, [<<"jid">>], [[J]]} -> J == JID;
+				    _ -> true
+				end,
+			if Allow ->
+				odbc_queries:update_t(<<"muc_registered">>,
+						      [<<"jid">>, <<"host">>,
+						       <<"nick">>],
+						      [SJID, SHost, SNick],
+						      [<<"jid='">>, SJID,
+						       <<"' and host='">>, SHost,
+						       <<"'">>]),
+				ok;
+			   true ->
+				false
+			end
+		end
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+export(_Server) ->
+    [{muc_room,
+      fun(Host, #muc_room{name_host = {Name, RoomHost}, opts = Opts}) ->
+              case str:suffix(Host, RoomHost) of
+                  true ->
+                      SName = ejabberd_odbc:escape(Name),
+                      SRoomHost = ejabberd_odbc:escape(RoomHost),
+                      SOpts = ejabberd_odbc:encode_term(Opts),
+                      [[<<"delete from muc_room where name='">>, SName,
+                        <<"' and host='">>, SRoomHost, <<"';">>],
+                       [<<"insert into muc_room(name, host, opts) ",
+                          "values (">>,
+                        <<"'">>, SName, <<"', '">>, SRoomHost,
+                        <<"', '">>, SOpts, <<"');">>]];
+                  false ->
+                      []
+              end
+      end},
+     {muc_registered,
+      fun(Host, #muc_registered{us_host = {{U, S}, RoomHost},
+                                nick = Nick}) ->
+              case str:suffix(Host, RoomHost) of
+                  true ->
+                      SJID = ejabberd_odbc:escape(
+                               jid:to_string(
+                                 jid:make(U, S, <<"">>))),
+                      SNick = ejabberd_odbc:escape(Nick),
+                      SRoomHost = ejabberd_odbc:escape(RoomHost),
+                      [[<<"delete from muc_registered where jid='">>,
+                        SJID, <<"' and host='">>, SRoomHost, <<"';">>],
+                       [<<"insert into muc_registered(jid, host, "
+                          "nick) values ('">>,
+                        SJID, <<"', '">>, SRoomHost, <<"', '">>, SNick,
+                        <<"');">>]];
+                  false ->
+                      []
+              end
+      end}].
+
+import(_LServer) ->
+    [{<<"select name, host, opts from muc_room;">>,
+      fun([Name, RoomHost, SOpts]) ->
+              Opts = mod_muc:opts_to_binary(ejabberd_odbc:decode_term(SOpts)),
+              #muc_room{name_host = {Name, RoomHost}, opts = Opts}
+      end},
+     {<<"select jid, host, nick from muc_registered;">>,
+      fun([J, RoomHost, Nick]) ->
+              #jid{user = U, server = S} = jid:from_string(J),
+              #muc_registered{us_host = {{U, S}, RoomHost},
+                              nick = Nick}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_offline.erl b/src/mod_offline.erl
index 54eda165..2cdd82ae 100644
--- a/src/mod_offline.erl
+++ b/src/mod_offline.erl
@@ -25,8 +25,6 @@
 
 -module(mod_offline).
 
--compile([{parse_transform, ejabberd_sql_pt}]).
-
 -author('alexey@process-one.net').
 
 -protocol({xep, 13, '1.2'}).
@@ -61,6 +59,7 @@
 	 get_queue_length/2,
 	 count_offline_messages/2,
 	 get_offline_els/2,
+	 find_x_expire/2,
 	 webadmin_page/3,
 	 webadmin_user/4,
 	 webadmin_user_parse_query/5]).
@@ -82,8 +81,6 @@
 
 -include("mod_offline.hrl").
 
--include("ejabberd_sql_pt.hrl").
-
 -define(PROCNAME, ejabberd_offline).
 
 -define(OFFLINE_TABLE_LOCK_THRESHOLD, 1000).
@@ -91,6 +88,25 @@
 %% default value for the maximum number of user messages
 -define(MAX_USER_MESSAGES, infinity).
 
+-type us() :: {binary(), binary()}.
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #offline_msg{}) -> ok | pass.
+-callback store_messages(binary(), us(), [#offline_msg{}],
+			 non_neg_integer(), non_neg_integer()) ->
+    {atomic, any()}.
+-callback pop_messages(binary(), binary()) ->
+    {atomic, [#offline_msg{}]} | {aborted, any()}.
+-callback remove_expired_messages(binary()) -> {atomic, any()}.
+-callback remove_old_messages(non_neg_integer(), binary()) -> {atomic, any()}.
+-callback remove_user(binary(), binary()) -> {atomic, any()}.
+-callback read_message_headers(binary(), binary()) -> any().
+-callback read_message(binary(), binary(), non_neg_integer()) ->
+    {ok, #offline_msg{}} | error.
+-callback remove_message(binary(), binary(), non_neg_integer()) -> ok.
+-callback read_all_messages(binary(), binary()) -> [#offline_msg{}].
+-callback remove_all_messages(binary(), binary()) -> {atomic, any()}.
+-callback count_messages(binary(), binary()) -> non_neg_integer().
+
 start_link(Host, Opts) ->
     Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
     ?GEN_SERVER:start_link({local, Proc}, ?MODULE,
@@ -115,14 +131,8 @@ stop(Host) ->
 %%====================================================================
 
 init([Host, Opts]) ->
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(offline_msg,
-			      [{disc_only_copies, [node()]}, {type, bag},
-			       {attributes, record_info(fields, offline_msg)}]),
-	  update_table();
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
 			     no_queue),
     ejabberd_hooks:add(offline_message_hook, Host, ?MODULE,
@@ -174,7 +184,7 @@ handle_info(#offline_msg{us = UserServer} = Msg, State) ->
     Len = length(Msgs),
     MaxOfflineMsgs = get_max_user_messages(AccessMaxOfflineMsgs,
                                            UserServer, Host),
-    store_offline_msg(Host, UserServer, Msgs, Len, MaxOfflineMsgs, DBType),
+    store_offline_msg(Host, UserServer, Msgs, Len, MaxOfflineMsgs),
     {noreply, State};
 
 handle_info(_Info, State) ->
@@ -210,68 +220,12 @@ terminate(_Reason, State) ->
 code_change(_OldVsn, State, _Extra) -> {ok, State}.
 
 store_offline_msg(Host, US, Msgs, Len, MaxOfflineMsgs) ->
-    DBType = gen_mod:db_type(Host, ?MODULE),
-    store_offline_msg(Host, US, Msgs, Len, MaxOfflineMsgs, DBType).
-
-store_offline_msg(_Host, US, Msgs, Len, MaxOfflineMsgs,
-		  mnesia) ->
-    F = fun () ->
-		Count = if MaxOfflineMsgs =/= infinity ->
-			       Len + count_mnesia_records(US);
-			   true -> 0
-			end,
-		if Count > MaxOfflineMsgs -> discard_warn_sender(Msgs);
-		   true ->
-		       if Len >= (?OFFLINE_TABLE_LOCK_THRESHOLD) ->
-			      mnesia:write_lock_table(offline_msg);
-			  true -> ok
-		       end,
-		       lists:foreach(fun (M) -> mnesia:write(M) end, Msgs)
-		end
-	end,
-    mnesia:transaction(F);
-store_offline_msg(Host, {User, _Server}, Msgs, Len, MaxOfflineMsgs, odbc) ->
-    Count = if MaxOfflineMsgs =/= infinity ->
-		   Len + count_offline_messages(User, Host);
-	       true -> 0
-	    end,
-    if Count > MaxOfflineMsgs -> discard_warn_sender(Msgs);
-       true ->
-	   Query = lists:map(fun (M) ->
-				     Username =
-					 ejabberd_odbc:escape((M#offline_msg.to)#jid.luser),
-				     From = M#offline_msg.from,
-				     To = M#offline_msg.to,
-				     Packet =
-					 jlib:replace_from_to(From, To,
-							      M#offline_msg.packet),
-				     NewPacket =
-					 jlib:add_delay_info(Packet, Host,
-							     M#offline_msg.timestamp,
-							     <<"Offline Storage">>),
-				     XML =
-					 ejabberd_odbc:escape(fxml:element_to_binary(NewPacket)),
-				     odbc_queries:add_spool_sql(Username, XML)
-			     end,
-			     Msgs),
-	   odbc_queries:add_spool(Host, Query)
-    end;
-store_offline_msg(Host, {User, _}, Msgs, Len, MaxOfflineMsgs,
-		  riak) ->
-    Count = if MaxOfflineMsgs =/= infinity ->
-                    Len + count_offline_messages(User, Host);
-               true -> 0
-            end,
-    if
-        Count > MaxOfflineMsgs ->
-            discard_warn_sender(Msgs);
-        true ->
-            lists:foreach(
-              fun(#offline_msg{us = US,
-                               timestamp = TS} = M) ->
-                      ejabberd_riak:put(M, offline_msg_schema(),
-					[{i, TS}, {'2i', [{<<"us">>, US}]}])
-              end, Msgs)
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    case Mod:store_messages(Host, US, Msgs, Len, MaxOfflineMsgs) of
+	{atomic, discard} ->
+	    discard_warn_sender(Msgs);
+	_ ->
+	    ok
     end.
 
 get_max_user_messages(AccessRule, {User, Server}, Host) ->
@@ -330,11 +284,11 @@ get_sm_items(_Acc, #jid{luser = U, lserver = S, lresource = R} = JID,
 	    BareJID = jid:to_string(jid:remove_resource(JID)),
 	    Pid ! dont_ask_offline,
 	    {result, lists:map(
-		       fun({Node, From, _OfflineMsg}) ->
+		       fun({Node, From, _To, _El}) ->
 			       #xmlel{name = <<"item">>,
 				      attrs = [{<<"jid">>, BareJID},
 					       {<<"node">>, Node},
-					       {<<"name">>, From}]}
+					       {<<"name">>, jid:to_string(From)}]}
 		       end, Hdrs)};
 	none ->
 	    {result, []}
@@ -452,46 +406,31 @@ handle_offline_fetch(#jid{luser = U, lserver = S, lresource = R}) ->
 	Pid when is_pid(Pid) ->
 	    Pid ! dont_ask_offline,
 	    lists:foreach(
-	      fun({Node, _, Msg}) ->
-		      case offline_msg_to_route(S, Msg) of
-			  {route, From, To, El} ->
-			      NewEl = set_offline_tag(El, Node),
-			      Pid ! {route, From, To, NewEl};
-			  error ->
-			      ok
-		      end
+	      fun({Node, From, To, El}) ->
+		      NewEl = set_offline_tag(El, Node),
+		      Pid ! {route, From, To, NewEl}
 	      end, read_message_headers(U, S))
     end.
 
-fetch_msg_by_node(To, <<Seq:20/binary, "+", From_s/binary>>) ->
-    case jid:from_string(From_s) of
-	From = #jid{} ->
-	    case gen_mod:db_type(To#jid.lserver, ?MODULE) of
-		odbc ->
-		    read_message(From, To, Seq, odbc);
-		DBType ->
-		    case binary_to_timestamp(Seq) of
-			undefined -> ok;
-			TS -> read_message(From, To, TS, DBType)
-		    end
-	    end;
-	error ->
-	    ok
+fetch_msg_by_node(To, Seq) ->
+    case catch binary_to_integer(Seq) of
+	I when is_integer(I), I >= 0 ->
+	    LUser = To#jid.luser,
+	    LServer = To#jid.lserver,
+	    Mod = gen_mod:db_mod(LServer, ?MODULE),
+	    Mod:read_message(LUser, LServer, I);
+	_ ->
+	    error
     end.
 
-remove_msg_by_node(To, <<Seq:20/binary, "+", From_s/binary>>) ->
-    case jid:from_string(From_s) of
-	From = #jid{} ->
-	    case gen_mod:db_type(To#jid.lserver, ?MODULE) of
-		odbc ->
-		    remove_message(From, To, Seq, odbc);
-		DBType ->
-		    case binary_to_timestamp(Seq) of
-			undefined -> ok;
-			TS -> remove_message(From, To, TS, DBType)
-		    end
-	    end;
-	error ->
+remove_msg_by_node(To, Seq) ->
+    case catch binary_to_integer(Seq) of
+	I when is_integer(I), I>= 0 ->
+	    LUser = To#jid.luser,
+	    LServer = To#jid.lserver,
+	    Mod = gen_mod:db_mod(LServer, ?MODULE),
+	    Mod:remove_message(LUser, LServer, I);
+	_ ->
 	    ok
     end.
 
@@ -648,21 +587,11 @@ find_x_expire(TimeStamp, [El | Els]) ->
 resend_offline_messages(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    US = {LUser, LServer},
-    F = fun () ->
-		Rs = mnesia:wread({offline_msg, US}),
-		mnesia:delete({offline_msg, US}),
-		Rs
-	end,
-    case mnesia:transaction(F) of
-      {atomic, Rs} ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:pop_messages(LUser, LServer) of
+      {ok, Rs} ->
 	  lists:foreach(fun (R) ->
-				ejabberd_sm !
-				  {route, R#offline_msg.from, R#offline_msg.to,
-				   jlib:add_delay_info(R#offline_msg.packet,
-						       LServer,
-						       R#offline_msg.timestamp,
-						       <<"Offline Storage">>)}
+				ejabberd_sm ! offline_msg_to_route(LServer, R)
 			end,
 			lists:keysort(#offline_msg.timestamp, Rs));
       _ -> ok
@@ -671,190 +600,47 @@ resend_offline_messages(User, Server) ->
 pop_offline_messages(Ls, User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    pop_offline_messages(Ls, LUser, LServer,
-			 gen_mod:db_type(LServer, ?MODULE)).
-
-pop_offline_messages(Ls, LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () ->
-		Rs = mnesia:wread({offline_msg, US}),
-		mnesia:delete({offline_msg, US}),
-		Rs
-	end,
-    case mnesia:transaction(F) of
-      {atomic, Rs} ->
-	  TS = p1_time_compat:timestamp(),
-	  Ls ++
-	    lists:map(fun (R) ->
-			      offline_msg_to_route(LServer, R)
-		      end,
-		      lists:filter(fun (R) ->
-					   case R#offline_msg.expire of
-					     never -> true;
-					     TimeStamp -> TS < TimeStamp
-					   end
-				   end,
-				   lists:keysort(#offline_msg.timestamp, Rs)));
-      _ -> Ls
-    end;
-pop_offline_messages(Ls, LUser, LServer, odbc) ->
-    case odbc_queries:get_and_del_spool_msg_t(LServer, LUser) of
-      {atomic, {selected, Rs}} ->
-	  Ls ++
-	    lists:flatmap(fun ({_, XML}) ->
-				  case fxml_stream:parse_element(XML) of
-				    {error, _Reason} ->
-                                          [];
-				    El ->
-                                          case offline_msg_to_route(LServer, El) of
-                                              error ->
-                                                  [];
-                                              RouteMsg ->
-                                                  [RouteMsg]
-                                          end
-				  end
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:pop_messages(LUser, LServer) of
+	{ok, Rs} ->
+	    TS = p1_time_compat:timestamp(),
+	    Ls ++
+		lists:map(fun (R) ->
+				  offline_msg_to_route(LServer, R)
 			  end,
-			  Rs);
-      _ -> Ls
-    end;
-pop_offline_messages(Ls, LUser, LServer, riak) ->
-    case ejabberd_riak:get_by_index(offline_msg, offline_msg_schema(),
-                                    <<"us">>, {LUser, LServer}) of
-        {ok, Rs} ->
-            try
-                lists:foreach(
-                  fun(#offline_msg{timestamp = T}) ->
-                          ok = ejabberd_riak:delete(offline_msg, T)
-                  end, Rs),
-                TS = p1_time_compat:timestamp(),
-                Ls ++ lists:map(
-                        fun (R) ->
-                                offline_msg_to_route(LServer, R)
-                        end,
-                        lists:filter(
-                          fun(R) ->
-                                  case R#offline_msg.expire of
-                                      never -> true;
-                                      TimeStamp -> TS < TimeStamp
-                                  end
-                          end,
-                          lists:keysort(#offline_msg.timestamp, Rs)))
-            catch _:{badmatch, _} ->
-                    Ls
-            end;
+			  lists:filter(
+			    fun(#offline_msg{packet = Pkt} = R) ->
+				    #xmlel{children = Els} = Pkt,
+				    Expire = case R#offline_msg.expire of
+						 undefined ->
+						     find_x_expire(TS, Els);
+						 Exp ->
+						     Exp
+					     end,
+				    case Expire of
+					never -> true;
+					TimeStamp -> TS < TimeStamp
+				    end
+			    end, Rs));
 	_ ->
 	    Ls
     end.
 
 remove_expired_messages(Server) ->
     LServer = jid:nameprep(Server),
-    remove_expired_messages(LServer,
-			    gen_mod:db_type(LServer, ?MODULE)).
-
-remove_expired_messages(_LServer, mnesia) ->
-    TimeStamp = p1_time_compat:timestamp(),
-    F = fun () ->
-		mnesia:write_lock_table(offline_msg),
-		mnesia:foldl(fun (Rec, _Acc) ->
-				     case Rec#offline_msg.expire of
-				       never -> ok;
-				       TS ->
-					   if TS < TimeStamp ->
-						  mnesia:delete_object(Rec);
-					      true -> ok
-					   end
-				     end
-			     end,
-			     ok, offline_msg)
-	end,
-    mnesia:transaction(F);
-remove_expired_messages(_LServer, odbc) -> {atomic, ok};
-remove_expired_messages(_LServer, riak) -> {atomic, ok}.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_expired_messages(LServer).
 
 remove_old_messages(Days, Server) ->
     LServer = jid:nameprep(Server),
-    remove_old_messages(Days, LServer,
-			gen_mod:db_type(LServer, ?MODULE)).
-
-remove_old_messages(Days, _LServer, mnesia) ->
-    S = p1_time_compat:system_time(seconds) - 60 * 60 * 24 * Days,
-    MegaSecs1 = S div 1000000,
-    Secs1 = S rem 1000000,
-    TimeStamp = {MegaSecs1, Secs1, 0},
-    F = fun () ->
-		mnesia:write_lock_table(offline_msg),
-		mnesia:foldl(fun (#offline_msg{timestamp = TS} = Rec,
-				  _Acc)
-				     when TS < TimeStamp ->
-				     mnesia:delete_object(Rec);
-				 (_Rec, _Acc) -> ok
-			     end,
-			     ok, offline_msg)
-	end,
-    mnesia:transaction(F);
-
-remove_old_messages(Days, LServer, odbc) ->
-    case catch ejabberd_odbc:sql_query(
-		 LServer,
-		 [<<"DELETE FROM spool"
-		   " WHERE created_at < "
-		   "DATE_SUB(CURDATE(), INTERVAL ">>,
-		  integer_to_list(Days), <<" DAY);">>]) of
-	{updated, N} ->
-	    ?INFO_MSG("~p message(s) deleted from offline spool", [N]);
-	_Error ->
-	    ?ERROR_MSG("Cannot delete message in offline spool: ~p", [_Error])
-    end,
-    {atomic, ok};
-remove_old_messages(_Days, _LServer, riak) ->
-    {atomic, ok}.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_old_messages(Days, LServer).
 
 remove_user(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    remove_user(LUser, LServer,
-		gen_mod:db_type(LServer, ?MODULE)).
-
-remove_user(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () -> mnesia:delete({offline_msg, US}) end,
-    mnesia:transaction(F);
-remove_user(LUser, LServer, odbc) ->
-    odbc_queries:del_spool_msg(LServer, LUser);
-remove_user(LUser, LServer, riak) ->
-    {atomic, ejabberd_riak:delete_by_index(offline_msg,
-                                           <<"us">>, {LUser, LServer})}.
-
-jid_to_binary(#jid{user = U, server = S, resource = R,
-                   luser = LU, lserver = LS, lresource = LR}) ->
-    #jid{user = iolist_to_binary(U),
-         server = iolist_to_binary(S),
-         resource = iolist_to_binary(R),
-         luser = iolist_to_binary(LU),
-         lserver = iolist_to_binary(LS),
-         lresource = iolist_to_binary(LR)}.
-
-update_table() ->
-    Fields = record_info(fields, offline_msg),
-    case mnesia:table_info(offline_msg, attributes) of
-        Fields ->
-            ejabberd_config:convert_table_to_binary(
-              offline_msg, Fields, bag,
-              fun(#offline_msg{us = {U, _}}) -> U end,
-              fun(#offline_msg{us = {U, S},
-                               from = From,
-                               to = To,
-                               packet = El} = R) ->
-                      R#offline_msg{us = {iolist_to_binary(U),
-                                          iolist_to_binary(S)},
-                                    from = jid_to_binary(From),
-                                    to = jid_to_binary(To),
-                                    packet = fxml:to_xmlel(El)}
-              end);
-        _ ->
-            ?INFO_MSG("Recreating offline_msg table", []),
-            mnesia:transform_table(offline_msg, ignore, Fields)
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_user(LUser, LServer).
 
 %% Helper functions:
 
@@ -880,255 +666,71 @@ webadmin_page(_, Host,
 webadmin_page(Acc, _, _) -> Acc.
 
 get_offline_els(LUser, LServer) ->
-    get_offline_els(LUser, LServer, gen_mod:db_type(LServer, ?MODULE)).
-
-get_offline_els(LUser, LServer, DBType)
-  when DBType == mnesia; DBType == riak ->
-    Msgs = read_all_msgs(LUser, LServer, DBType),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Hdrs = Mod:read_message_headers(LUser, LServer),
     lists:map(
-      fun(Msg) ->
-              {route, From, To, Packet} = offline_msg_to_route(LServer, Msg),
-              jlib:replace_from_to(From, To, Packet)
-      end, Msgs);
-get_offline_els(LUser, LServer, odbc) ->
-    case catch ejabberd_odbc:sql_query(
-                 LServer,
-                 ?SQL("select @(xml)s from spool where "
-                      "username=%(LUser)s order by seq")) of
-        {selected, Rs} ->
-            lists:flatmap(
-              fun({XML}) ->
-                      case fxml_stream:parse_element(XML) of
-                          #xmlel{} = El ->
-                              case offline_msg_to_route(LServer, El) of
-                                  {route, _, _, NewEl} ->
-                                      [NewEl];
-                                  error ->
-                                      []
-                              end;
-                          _ ->
-                              []
-                      end
-              end, Rs);
-        _ ->
-            []
-    end.
+      fun({_Seq, From, To, Packet}) ->
+	      jlib:replace_from_to(From, To, Packet)
+      end, Hdrs).
 
 offline_msg_to_route(LServer, #offline_msg{} = R) ->
-    {route, R#offline_msg.from, R#offline_msg.to,
-     jlib:add_delay_info(R#offline_msg.packet, LServer, R#offline_msg.timestamp,
-			 <<"Offline Storage">>)};
-offline_msg_to_route(_LServer, #xmlel{} = El) ->
-    To = jid:from_string(fxml:get_tag_attr_s(<<"to">>, El)),
-    From = jid:from_string(fxml:get_tag_attr_s(<<"from">>, El)),
-    if (To /= error) and (From /= error) ->
-            {route, From, To, El};
-       true ->
-            error
-    end.
-
-binary_to_timestamp(TS) ->
-    case catch jlib:binary_to_integer(TS) of
-	Int when is_integer(Int) ->
-	    Secs = Int div 1000000,
-	    USec = Int rem 1000000,
-	    MSec = Secs div 1000000,
-	    Sec = Secs rem 1000000,
-	    {MSec, Sec, USec};
-	_ ->
-	    undefined
-    end.
-
-timestamp_to_binary({MS, S, US}) ->
-    format_timestamp(integer_to_list((MS * 1000000 + S) * 1000000 + US)).
-
-format_timestamp(TS) ->
-    iolist_to_binary(io_lib:format("~20..0s", [TS])).
-
-offline_msg_to_header(#offline_msg{from = From, timestamp = Int} = Msg) ->
-    TS = timestamp_to_binary(Int),
-    From_s = jid:to_string(From),
-    {<<TS/binary, "+", From_s/binary>>, From_s, Msg}.
+    El = case R#offline_msg.timestamp of
+	     undefined ->
+		 R#offline_msg.packet;
+	     TS ->
+		 jlib:add_delay_info(R#offline_msg.packet, LServer, TS,
+				     <<"Offline Storage">>)
+	 end,
+    {route, R#offline_msg.from, R#offline_msg.to, El}.
 
 read_message_headers(LUser, LServer) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    read_message_headers(LUser, LServer, DBType).
-
-read_message_headers(LUser, LServer, mnesia) ->
-    Msgs = mnesia:dirty_read({offline_msg, {LUser, LServer}}),
-    Hdrs = lists:map(fun offline_msg_to_header/1, Msgs),
-    lists:keysort(1, Hdrs);
-read_message_headers(LUser, LServer, riak) ->
-    case ejabberd_riak:get_by_index(
-           offline_msg, offline_msg_schema(),
-	   <<"us">>, {LUser, LServer}) of
-        {ok, Rs} ->
-	    Hdrs = lists:map(fun offline_msg_to_header/1, Rs),
-	    lists:keysort(1, Hdrs);
-	_Err ->
-	    []
-    end;
-read_message_headers(LUser, LServer, odbc) ->
-    Username = ejabberd_odbc:escape(LUser),
-    case catch ejabberd_odbc:sql_query(
-		 LServer, [<<"select xml, seq from spool where username ='">>,
-			   Username, <<"' order by seq;">>]) of
-	{selected, [<<"xml">>, <<"seq">>], Rows} ->
-	    Hdrs = lists:flatmap(
-		     fun([XML, Seq]) ->
-			     try
-				 #xmlel{} = El = fxml_stream:parse_element(XML),
-				 From = fxml:get_tag_attr_s(<<"from">>, El),
-				 #jid{} = jid:from_string(From),
-				 TS = format_timestamp(Seq),
-				 [{<<TS/binary, "+", From/binary>>, From, El}]
-			     catch _:_ -> []
-			     end
-		     end, Rows),
-	    lists:keysort(1, Hdrs);
-	_Err ->
-	    []
-    end.
-
-read_message(_From, To, TS, mnesia) ->
-    {U, S, _} = jid:tolower(To),
-    case mnesia:dirty_match_object(
-	   offline_msg, #offline_msg{us = {U, S}, timestamp = TS, _ = '_'}) of
-	[Msg|_] ->
-	    {ok, Msg};
-	_ ->
-	    error
-    end;
-read_message(_From, _To, TS, riak) ->
-    case ejabberd_riak:get(offline_msg, offline_msg_schema(), TS) of
-	{ok, Msg} ->
-	    {ok, Msg};
-	_ ->
-	    error
-    end;
-read_message(_From, To, Seq, odbc) ->
-    {LUser, LServer, _} = jid:tolower(To),
-    Username = ejabberd_odbc:escape(LUser),
-    SSeq = ejabberd_odbc:escape(Seq),
-    case ejabberd_odbc:sql_query(
-	   LServer,
-	   [<<"select xml from spool  where username='">>, Username,
-	    <<"'  and seq='">>, SSeq, <<"';">>]) of
-	{selected, [<<"xml">>], [[RawXML]|_]} ->
-	    case fxml_stream:parse_element(RawXML) of
-		#xmlel{} = El -> {ok, El};
-		{error, _} -> error
-	    end;
-	_ ->
-	    error
-    end.
-
-remove_message(_From, To, TS, mnesia) ->
-    {U, S, _} = jid:tolower(To),
-    Msgs = mnesia:dirty_match_object(
-	     offline_msg, #offline_msg{us = {U, S}, timestamp = TS, _ = '_'}),
-    lists:foreach(
-      fun(Msg) ->
-	      mnesia:dirty_delete_object(Msg)
-      end, Msgs);
-remove_message(_From, _To, TS, riak) ->
-    ejabberd_riak:delete(offline_msg, TS),
-    ok;
-remove_message(_From, To, Seq, odbc) ->
-    {LUser, LServer, _} = jid:tolower(To),
-    Username = ejabberd_odbc:escape(LUser),
-    SSeq = ejabberd_odbc:escape(Seq),
-    ejabberd_odbc:sql_query(
-      LServer,
-      [<<"delete from spool  where username='">>, Username,
-       <<"'  and seq='">>, SSeq, <<"';">>]),
-    ok.
-
-read_all_msgs(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    lists:keysort(#offline_msg.timestamp,
-		  mnesia:dirty_read({offline_msg, US}));
-read_all_msgs(LUser, LServer, riak) ->
-    case ejabberd_riak:get_by_index(
-           offline_msg, offline_msg_schema(),
-	   <<"us">>, {LUser, LServer}) of
-        {ok, Rs} ->
-            lists:keysort(#offline_msg.timestamp, Rs);
-        _Err ->
-            []
-    end;
-read_all_msgs(LUser, LServer, odbc) ->
-    case catch ejabberd_odbc:sql_query(
-                 LServer,
-                 ?SQL("select @(xml)s from spool where "
-                      "username=%(LUser)s order by seq")) of
-        {selected, Rs} ->
-            lists:flatmap(
-              fun({XML}) ->
-                      case fxml_stream:parse_element(XML) of
-                          {error, _Reason} -> [];
-                          El -> [El]
-                      end
-              end,
-              Rs);
-        _ -> []
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    lists:map(
+      fun({Seq, From, To, El}) ->
+	      Node = integer_to_binary(Seq),
+	      {Node, From, To, El}
+      end, Mod:read_message_headers(LUser, LServer)).
 
-format_user_queue(Msgs, DBType) when DBType == mnesia; DBType == riak ->
-    lists:map(fun (#offline_msg{timestamp = TimeStamp,
-				from = From, to = To,
-				packet =
-				    #xmlel{name = Name, attrs = Attrs,
-					   children = Els}} =
-		       Msg) ->
-		      ID = jlib:encode_base64((term_to_binary(Msg))),
-		      {{Year, Month, Day}, {Hour, Minute, Second}} =
-			  calendar:now_to_local_time(TimeStamp),
-		      Time =
-			  iolist_to_binary(io_lib:format("~w-~.2.0w-~.2.0w ~.2.0w:~.2.0w:~.2.0w",
-							 [Year, Month, Day,
-							  Hour, Minute,
-							  Second])),
-		      SFrom = jid:to_string(From),
-		      STo = jid:to_string(To),
-		      Attrs2 = jlib:replace_from_to_attrs(SFrom, STo, Attrs),
-		      Packet = #xmlel{name = Name, attrs = Attrs2,
-				      children = Els},
-		      FPacket = ejabberd_web_admin:pretty_print_xml(Packet),
-		      ?XE(<<"tr">>,
-			  [?XAE(<<"td">>, [{<<"class">>, <<"valign">>}],
-				[?INPUT(<<"checkbox">>, <<"selected">>, ID)]),
-			   ?XAC(<<"td">>, [{<<"class">>, <<"valign">>}], Time),
-			   ?XAC(<<"td">>, [{<<"class">>, <<"valign">>}], SFrom),
-			   ?XAC(<<"td">>, [{<<"class">>, <<"valign">>}], STo),
-			   ?XAE(<<"td">>, [{<<"class">>, <<"valign">>}],
-				[?XC(<<"pre">>, FPacket)])])
-	      end,
-	      Msgs);
-format_user_queue(Msgs, odbc) ->
-    lists:map(fun (#xmlel{} = Msg) ->
-		      ID = jlib:encode_base64((term_to_binary(Msg))),
-		      Packet = Msg,
-		      FPacket = ejabberd_web_admin:pretty_print_xml(Packet),
-		      ?XE(<<"tr">>,
-			  [?XAE(<<"td">>, [{<<"class">>, <<"valign">>}],
-				[?INPUT(<<"checkbox">>, <<"selected">>, ID)]),
-			   ?XAE(<<"td">>, [{<<"class">>, <<"valign">>}],
-				[?XC(<<"pre">>, FPacket)])])
-	      end,
-	      Msgs).
+format_user_queue(Hdrs) ->
+    lists:map(
+      fun({Seq, From, To, El}) ->
+	      ID = integer_to_binary(Seq),
+	      FPacket = ejabberd_web_admin:pretty_print_xml(El),
+	      SFrom = jid:to_string(From),
+	      STo = jid:to_string(To),
+	      Stamp = fxml:get_path_s(El, [{elem, <<"delay">>},
+					   {attr, <<"stamp">>}]),
+	      Time = case jlib:datetime_string_to_timestamp(Stamp) of
+			 {_, _, _} = Now ->
+			     {{Year, Month, Day}, {Hour, Minute, Second}} =
+				 calendar:now_to_local_time(Now),
+			     iolist_to_binary(
+			       io_lib:format(
+				 "~w-~.2.0w-~.2.0w ~.2.0w:~.2.0w:~.2.0w",
+				 [Year, Month, Day, Hour, Minute,
+				  Second]));
+			 _ ->
+			     <<"">>
+		     end,
+	      ?XE(<<"tr">>,
+		  [?XAE(<<"td">>, [{<<"class">>, <<"valign">>}],
+			[?INPUT(<<"checkbox">>, <<"selected">>, ID)]),
+		   ?XAC(<<"td">>, [{<<"class">>, <<"valign">>}], Time),
+		   ?XAC(<<"td">>, [{<<"class">>, <<"valign">>}], SFrom),
+		   ?XAC(<<"td">>, [{<<"class">>, <<"valign">>}], STo),
+		   ?XAE(<<"td">>, [{<<"class">>, <<"valign">>}],
+			[?XC(<<"pre">>, FPacket)])])
+      end, Hdrs).
 
 user_queue(User, Server, Query, Lang) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
     US = {LUser, LServer},
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    Res = user_queue_parse_query(LUser, LServer, Query,
-				 DBType),
-    MsgsAll = read_all_msgs(LUser, LServer, DBType),
-    Msgs = get_messages_subset(US, Server, MsgsAll,
-			       DBType),
-    FMsgs = format_user_queue(Msgs, DBType),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Res = user_queue_parse_query(LUser, LServer, Query),
+    HdrsAll = Mod:read_message_headers(LUser, LServer),
+    Hdrs = get_messages_subset(US, Server, HdrsAll),
+    FMsgs = format_user_queue(Hdrs),
     [?XC(<<"h1">>,
 	 list_to_binary(io_lib:format(?T(<<"~s's Offline Messages Queue">>),
                                       [us_to_list(US)])))]
@@ -1158,96 +760,24 @@ user_queue(User, Server, Query, Lang) ->
 	       ?INPUTT(<<"submit">>, <<"delete">>,
 		       <<"Delete Selected">>)])].
 
-user_queue_parse_query(LUser, LServer, Query, mnesia) ->
-    US = {LUser, LServer},
-    case lists:keysearch(<<"delete">>, 1, Query) of
-      {value, _} ->
-	  Msgs = lists:keysort(#offline_msg.timestamp,
-			       mnesia:dirty_read({offline_msg, US})),
-	  F = fun () ->
-		      lists:foreach(fun (Msg) ->
-					    ID =
-						jlib:encode_base64((term_to_binary(Msg))),
-					    case lists:member({<<"selected">>,
-							       ID},
-							      Query)
-						of
-					      true -> mnesia:delete_object(Msg);
-					      false -> ok
-					    end
-				    end,
-				    Msgs)
-	      end,
-	  mnesia:transaction(F),
-	  ok;
-      false -> nothing
-    end;
-user_queue_parse_query(LUser, LServer, Query, riak) ->
+user_queue_parse_query(LUser, LServer, Query) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
     case lists:keysearch(<<"delete">>, 1, Query) of
-        {value, _} ->
-            Msgs = read_all_msgs(LUser, LServer, riak),
-            lists:foreach(
-              fun (Msg) ->
-                      ID = jlib:encode_base64((term_to_binary(Msg))),
-                      case lists:member({<<"selected">>, ID}, Query) of
-                          true ->
-                              ejabberd_riak:delete(offline_msg,
-                                                   Msg#offline_msg.timestamp);
-                          false ->
-                              ok
-                      end
-              end,
-              Msgs),
-            ok;
-        false ->
-            nothing
-    end;
-user_queue_parse_query(LUser, LServer, Query, odbc) ->
-    Username = ejabberd_odbc:escape(LUser),
-    case lists:keysearch(<<"delete">>, 1, Query) of
-      {value, _} ->
-	  Msgs = case catch ejabberd_odbc:sql_query(LServer,
-						    [<<"select xml, seq from spool  where username='">>,
-						     Username,
-						     <<"'  order by seq;">>])
-		     of
-		   {selected, [<<"xml">>, <<"seq">>], Rs} ->
-		       lists:flatmap(fun ([XML, Seq]) ->
-					     case fxml_stream:parse_element(XML)
-						 of
-					       {error, _Reason} -> [];
-					       El -> [{El, Seq}]
-					     end
-				     end,
-				     Rs);
-		   _ -> []
-		 end,
-	  F = fun () ->
-		      lists:foreach(fun ({Msg, Seq}) ->
-					    ID =
-						jlib:encode_base64((term_to_binary(Msg))),
-					    case lists:member({<<"selected">>,
-							       ID},
-							      Query)
-						of
-					      true ->
-						  SSeq =
-						      ejabberd_odbc:escape(Seq),
-						  catch
-						    ejabberd_odbc:sql_query(LServer,
-									    [<<"delete from spool  where username='">>,
-									     Username,
-									     <<"'  and seq='">>,
-									     SSeq,
-									     <<"';">>]);
-					      false -> ok
-					    end
-				    end,
-				    Msgs)
-	      end,
-	  mnesia:transaction(F),
-	  ok;
-      false -> nothing
+	{value, _} ->
+	    case lists:keyfind(<<"selected">>, 1, Query) of
+		{_, Seq} ->
+		    case catch binary_to_integer(Seq) of
+			I when is_integer(I), I>=0 ->
+			    Mod:remove_message(LUser, LServer, I),
+			    ok;
+			_ ->
+			    nothing
+		    end;
+		false ->
+		    nothing
+	    end;
+	_ ->
+	    nothing
     end.
 
 us_to_list({User, Server}) ->
@@ -1256,7 +786,7 @@ us_to_list({User, Server}) ->
 get_queue_length(LUser, LServer) ->
     count_offline_messages(LUser, LServer).
 
-get_messages_subset(User, Host, MsgsAll, DBType) ->
+get_messages_subset(User, Host, MsgsAll) ->
     Access = gen_mod:get_module_opt(Host, ?MODULE, access_max_user_messages,
                                     fun(A) when is_atom(A) -> A end,
 				    max_user_offline_messages),
@@ -1267,33 +797,20 @@ get_messages_subset(User, Host, MsgsAll, DBType) ->
 		       _ -> 100
 		     end,
     Length = length(MsgsAll),
-    get_messages_subset2(MaxOfflineMsgs, Length, MsgsAll,
-			 DBType).
+    get_messages_subset2(MaxOfflineMsgs, Length, MsgsAll).
 
-get_messages_subset2(Max, Length, MsgsAll, _DBType)
-    when Length =< Max * 2 ->
+get_messages_subset2(Max, Length, MsgsAll) when Length =< Max * 2 ->
     MsgsAll;
-get_messages_subset2(Max, Length, MsgsAll, DBType)
-  when DBType == mnesia; DBType == riak ->
+get_messages_subset2(Max, Length, MsgsAll) ->
     FirstN = Max,
     {MsgsFirstN, Msgs2} = lists:split(FirstN, MsgsAll),
     MsgsLastN = lists:nthtail(Length - FirstN - FirstN,
 			      Msgs2),
     NoJID = jid:make(<<"...">>, <<"...">>, <<"">>),
-    IntermediateMsg = #offline_msg{timestamp = p1_time_compat:timestamp(),
-				   from = NoJID, to = NoJID,
-				   packet =
-				       #xmlel{name = <<"...">>, attrs = [],
-					      children = []}},
-    MsgsFirstN ++ [IntermediateMsg] ++ MsgsLastN;
-get_messages_subset2(Max, Length, MsgsAll, odbc) ->
-    FirstN = Max,
-    {MsgsFirstN, Msgs2} = lists:split(FirstN, MsgsAll),
-    MsgsLastN = lists:nthtail(Length - FirstN - FirstN,
-			      Msgs2),
+    Seq = <<"0">>,
     IntermediateMsg = #xmlel{name = <<"...">>, attrs = [],
 			     children = []},
-    MsgsFirstN ++ [IntermediateMsg] ++ MsgsLastN.
+    MsgsFirstN ++ [{Seq, NoJID, NoJID, IntermediateMsg}] ++ MsgsLastN.
 
 webadmin_user(Acc, User, Server, Lang) ->
     QueueLen = count_offline_messages(jid:nodeprep(User),
@@ -1310,25 +827,8 @@ webadmin_user(Acc, User, Server, Lang) ->
 delete_all_msgs(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    delete_all_msgs(LUser, LServer,
-		    gen_mod:db_type(LServer, ?MODULE)).
-
-delete_all_msgs(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () ->
-		mnesia:write_lock_table(offline_msg),
-		lists:foreach(fun (Msg) -> mnesia:delete_object(Msg)
-			      end,
-			      mnesia:dirty_read({offline_msg, US}))
-	end,
-    mnesia:transaction(F);
-delete_all_msgs(LUser, LServer, riak) ->
-    Res = ejabberd_riak:delete_by_index(offline_msg,
-                                        <<"us">>, {LUser, LServer}),
-    {atomic, Res};
-delete_all_msgs(LUser, LServer, odbc) ->
-    odbc_queries:del_spool_msg(LServer, LUser),
-    {atomic, ok}.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_all_messages(LUser, LServer).
 
 webadmin_user_parse_query(_, <<"removealloffline">>,
 			  User, Server, _Query) ->
@@ -1350,112 +850,20 @@ webadmin_user_parse_query(Acc, _Action, _User, _Server,
 count_offline_messages(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    count_offline_messages(LUser, LServer, DBType).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:count_messages(LUser, LServer).
 
-count_offline_messages(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () ->
-		count_mnesia_records(US)
-	end,
-    case catch mnesia:async_dirty(F) of
-      I when is_integer(I) -> I;
-      _ -> 0
-    end;
-count_offline_messages(LUser, LServer, odbc) ->
-    case catch ejabberd_odbc:sql_query(
-                 LServer,
-                 ?SQL("select @(count(*))d from spool "
-                      "where username=%(LUser)s")) of
-        {selected, [{Res}]} ->
-            Res;
-        _ -> 0
-    end;
-count_offline_messages(LUser, LServer, riak) ->
-    case ejabberd_riak:count_by_index(
-           offline_msg, <<"us">>, {LUser, LServer}) of
-        {ok, Res} ->
-            Res;
-        _ ->
-            0
-    end.
-
-%% Return the number of records matching a given match expression.
-%% This function is intended to be used inside a Mnesia transaction.
-%% The count has been written to use the fewest possible memory by
-%% getting the record by small increment and by using continuation.
--define(BATCHSIZE, 100).
-
-count_mnesia_records(US) ->
-    MatchExpression = #offline_msg{us = US,  _ = '_'},
-    case mnesia:select(offline_msg, [{MatchExpression, [], [[]]}],
-		       ?BATCHSIZE, read) of
-	{Result, Cont} ->
-	    Count = length(Result),
-	    count_records_cont(Cont, Count);
-	'$end_of_table' ->
-	    0
-    end.
-
-count_records_cont(Cont, Count) ->
-    case mnesia:select(Cont) of
-	{Result, Cont} ->
-	    NewCount = Count + length(Result),
-	    count_records_cont(Cont, NewCount);
-	'$end_of_table' ->
-	    Count
-    end.
-
-offline_msg_schema() ->
-    {record_info(fields, offline_msg), #offline_msg{}}.
-
-export(_Server) ->
-    [{offline_msg,
-      fun(Host, #offline_msg{us = {LUser, LServer},
-                             timestamp = TimeStamp, from = From, to = To,
-                             packet = Packet})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              Packet1 = jlib:replace_from_to(From, To, Packet),
-              Packet2 = jlib:add_delay_info(Packet1, LServer, TimeStamp,
-                                            <<"Offline Storage">>),
-              XML = ejabberd_odbc:escape(fxml:element_to_binary(Packet2)),
-              [[<<"delete from spool where username='">>, Username, <<"';">>],
-               [<<"insert into spool(username, xml) values ('">>,
-                Username, <<"', '">>, XML, <<"');">>]];
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select username, xml from spool;">>,
-      fun([LUser, XML]) ->
-              El = #xmlel{} = fxml_stream:parse_element(XML),
-              From = #jid{} = jid:from_string(
-                                fxml:get_attr_s(<<"from">>, El#xmlel.attrs)),
-              To = #jid{} = jid:from_string(
-                              fxml:get_attr_s(<<"to">>, El#xmlel.attrs)),
-              Stamp = fxml:get_path_s(El, [{elem, <<"delay">>},
-                                          {attr, <<"stamp">>}]),
-              TS = case jlib:datetime_string_to_timestamp(Stamp) of
-                       {_, _, _} = Now ->
-                           Now;
-                       undefined ->
-                           p1_time_compat:timestamp()
-                   end,
-              Expire = find_x_expire(TS, El#xmlel.children),
-              #offline_msg{us = {LUser, LServer},
-                           from = From, to = To,
-                           timestamp = TS, expire = Expire}
-      end}].
-
-import(_LServer, mnesia, #offline_msg{} = Msg) ->
-    mnesia:dirty_write(Msg);
-import(_LServer, riak, #offline_msg{us = US, timestamp = TS} = M) ->
-    ejabberd_riak:put(M, offline_msg_schema(),
-		      [{i, TS}, {'2i', [{<<"us">>, US}]}]);
-import(_, _, _) ->
-    pass.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
+
+import(LServer, DBType, Data) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, Data).
 
 mod_opt_type(access_max_user_messages) ->
     fun (A) -> A end;
diff --git a/src/mod_offline_mnesia.erl b/src/mod_offline_mnesia.erl
new file mode 100644
index 00000000..6a1d9e30
--- /dev/null
+++ b/src/mod_offline_mnesia.erl
@@ -0,0 +1,232 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 15 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_offline_mnesia).
+
+-behaviour(mod_offline).
+
+-export([init/2, store_messages/5, pop_messages/2, remove_expired_messages/1,
+	 remove_old_messages/2, remove_user/2, read_message_headers/2,
+	 read_message/3, remove_message/3, read_all_messages/2,
+	 remove_all_messages/2, count_messages/2, import/2]).
+
+-include("jlib.hrl").
+-include("mod_offline.hrl").
+-include("logger.hrl").
+
+-define(OFFLINE_TABLE_LOCK_THRESHOLD, 1000).
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(offline_msg,
+			[{disc_only_copies, [node()]}, {type, bag},
+			 {attributes, record_info(fields, offline_msg)}]),
+    update_table().
+
+store_messages(_Host, US, Msgs, Len, MaxOfflineMsgs) ->
+    F = fun () ->
+		Count = if MaxOfflineMsgs =/= infinity ->
+				Len + count_mnesia_records(US);
+			   true -> 0
+			end,
+		if Count > MaxOfflineMsgs -> discard;
+		   true ->
+			if Len >= (?OFFLINE_TABLE_LOCK_THRESHOLD) ->
+				mnesia:write_lock_table(offline_msg);
+			   true -> ok
+			end,
+			lists:foreach(fun (M) -> mnesia:write(M) end, Msgs)
+		end
+	end,
+    mnesia:transaction(F).
+
+pop_messages(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		Rs = mnesia:wread({offline_msg, US}),
+		mnesia:delete({offline_msg, US}),
+		Rs
+	end,
+    case mnesia:transaction(F) of
+	{atomic, L} ->
+	    {ok, lists:keysort(#offline_msg.timestamp, L)};
+	{aborted, Reason} ->
+	    {error, Reason}
+    end.
+
+remove_expired_messages(_LServer) ->
+    TimeStamp = p1_time_compat:timestamp(),
+    F = fun () ->
+		mnesia:write_lock_table(offline_msg),
+		mnesia:foldl(fun (Rec, _Acc) ->
+				     case Rec#offline_msg.expire of
+					 never -> ok;
+					 TS ->
+					     if TS < TimeStamp ->
+						     mnesia:delete_object(Rec);
+						true -> ok
+					     end
+				     end
+			     end,
+			     ok, offline_msg)
+	end,
+    mnesia:transaction(F).
+
+remove_old_messages(Days, _LServer) ->
+    S = p1_time_compat:system_time(seconds) - 60 * 60 * 24 * Days,
+    MegaSecs1 = S div 1000000,
+    Secs1 = S rem 1000000,
+    TimeStamp = {MegaSecs1, Secs1, 0},
+    F = fun () ->
+		mnesia:write_lock_table(offline_msg),
+		mnesia:foldl(fun (#offline_msg{timestamp = TS} = Rec,
+				  _Acc)
+				     when TS < TimeStamp ->
+				     mnesia:delete_object(Rec);
+				 (_Rec, _Acc) -> ok
+			     end,
+			     ok, offline_msg)
+	end,
+    mnesia:transaction(F).
+
+remove_user(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () -> mnesia:delete({offline_msg, US}) end,
+    mnesia:transaction(F).
+
+read_message_headers(LUser, LServer) ->
+    Msgs = mnesia:dirty_read({offline_msg, {LUser, LServer}}),
+    Hdrs = lists:map(
+	     fun(#offline_msg{from = From, to = To, packet = Pkt,
+			      timestamp = TS}) ->
+		     Seq = now_to_integer(TS),
+		     NewPkt = jlib:add_delay_info(Pkt, LServer, TS,
+						  <<"Offline Storage">>),
+		     {Seq, From, To, NewPkt}
+	     end, Msgs),
+    lists:keysort(1, Hdrs).
+
+read_message(LUser, LServer, I) ->
+    US = {LUser, LServer},
+    TS = integer_to_now(I),
+    case mnesia:dirty_match_object(
+	   offline_msg, #offline_msg{us = US, timestamp = TS, _ = '_'}) of
+	[Msg|_] ->
+	    {ok, Msg};
+	_ ->
+	    error
+    end.
+
+remove_message(LUser, LServer, I) ->
+    US = {LUser, LServer},
+    TS = integer_to_now(I),
+    Msgs = mnesia:dirty_match_object(
+	     offline_msg, #offline_msg{us = US, timestamp = TS, _ = '_'}),
+    lists:foreach(
+      fun(Msg) ->
+	      mnesia:dirty_delete_object(Msg)
+      end, Msgs).
+
+read_all_messages(LUser, LServer) ->
+    US = {LUser, LServer},
+    lists:keysort(#offline_msg.timestamp,
+		  mnesia:dirty_read({offline_msg, US})).
+
+remove_all_messages(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		mnesia:write_lock_table(offline_msg),
+		lists:foreach(fun (Msg) -> mnesia:delete_object(Msg) end,
+			      mnesia:dirty_read({offline_msg, US}))
+	end,
+    mnesia:transaction(F).
+
+count_messages(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		count_mnesia_records(US)
+	end,
+    case catch mnesia:async_dirty(F) of
+	I when is_integer(I) -> I;
+	_ -> 0
+    end.
+
+import(_LServer, #offline_msg{} = Msg) ->
+    mnesia:dirty_write(Msg).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+%% Return the number of records matching a given match expression.
+%% This function is intended to be used inside a Mnesia transaction.
+%% The count has been written to use the fewest possible memory by
+%% getting the record by small increment and by using continuation.
+-define(BATCHSIZE, 100).
+
+count_mnesia_records(US) ->
+    MatchExpression = #offline_msg{us = US,  _ = '_'},
+    case mnesia:select(offline_msg, [{MatchExpression, [], [[]]}],
+		       ?BATCHSIZE, read) of
+	{Result, Cont} ->
+	    Count = length(Result),
+	    count_records_cont(Cont, Count);
+	'$end_of_table' ->
+	    0
+    end.
+
+count_records_cont(Cont, Count) ->
+    case mnesia:select(Cont) of
+	{Result, Cont} ->
+	    NewCount = Count + length(Result),
+	    count_records_cont(Cont, NewCount);
+	'$end_of_table' ->
+	    Count
+    end.
+
+jid_to_binary(#jid{user = U, server = S, resource = R,
+                   luser = LU, lserver = LS, lresource = LR}) ->
+    #jid{user = iolist_to_binary(U),
+         server = iolist_to_binary(S),
+         resource = iolist_to_binary(R),
+         luser = iolist_to_binary(LU),
+         lserver = iolist_to_binary(LS),
+         lresource = iolist_to_binary(LR)}.
+
+now_to_integer({MS, S, US}) ->
+    (MS * 1000000 + S) * 1000000 + US.
+
+integer_to_now(Int) ->
+    Secs = Int div 1000000,
+    USec = Int rem 1000000,
+    MSec = Secs div 1000000,
+    Sec = Secs rem 1000000,
+    {MSec, Sec, USec}.
+
+update_table() ->
+    Fields = record_info(fields, offline_msg),
+    case mnesia:table_info(offline_msg, attributes) of
+        Fields ->
+            ejabberd_config:convert_table_to_binary(
+              offline_msg, Fields, bag,
+              fun(#offline_msg{us = {U, _}}) -> U end,
+              fun(#offline_msg{us = {U, S},
+                               from = From,
+                               to = To,
+                               packet = El} = R) ->
+                      R#offline_msg{us = {iolist_to_binary(U),
+                                          iolist_to_binary(S)},
+                                    from = jid_to_binary(From),
+                                    to = jid_to_binary(To),
+                                    packet = fxml:to_xmlel(El)}
+              end);
+        _ ->
+            ?INFO_MSG("Recreating offline_msg table", []),
+            mnesia:transform_table(offline_msg, ignore, Fields)
+    end.
diff --git a/src/mod_offline_riak.erl b/src/mod_offline_riak.erl
new file mode 100644
index 00000000..217e8f82
--- /dev/null
+++ b/src/mod_offline_riak.erl
@@ -0,0 +1,153 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 15 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_offline_riak).
+
+-behaviour(mod_offline).
+
+-export([init/2, store_messages/5, pop_messages/2, remove_expired_messages/1,
+	 remove_old_messages/2, remove_user/2, read_message_headers/2,
+	 read_message/3, remove_message/3, read_all_messages/2,
+	 remove_all_messages/2, count_messages/2, import/2]).
+
+-include("jlib.hrl").
+-include("mod_offline.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+store_messages(Host, {User, _}, Msgs, Len, MaxOfflineMsgs) ->
+    Count = if MaxOfflineMsgs =/= infinity ->
+                    Len + count_messages(User, Host);
+               true -> 0
+            end,
+    if
+        Count > MaxOfflineMsgs ->
+            {atomic, discard};
+        true ->
+	    try
+		lists:foreach(
+		  fun(#offline_msg{us = US,
+				   timestamp = TS} = M) ->
+			  ok = ejabberd_riak:put(
+				 M, offline_msg_schema(),
+				 [{i, TS}, {'2i', [{<<"us">>, US}]}])
+		  end, Msgs),
+		{atomic, ok}
+	    catch _:{badmatch, Err} ->
+		    {atomic, Err}
+	    end
+    end.
+
+pop_messages(LUser, LServer) ->
+    case ejabberd_riak:get_by_index(offline_msg, offline_msg_schema(),
+                                    <<"us">>, {LUser, LServer}) of
+        {ok, Rs} ->
+	    try
+                lists:foreach(
+                  fun(#offline_msg{timestamp = T}) ->
+                          ok = ejabberd_riak:delete(offline_msg, T)
+                  end, Rs),
+		{ok, lists:keysort(#offline_msg.timestamp, Rs)}
+	    catch _:{badmatch, Err} ->
+		    Err
+	    end;
+	Err ->
+	    Err
+    end.
+
+remove_expired_messages(_LServer) ->
+    %% TODO
+    {atomic, ok}.
+
+remove_old_messages(_Days, _LServer) ->
+    %% TODO
+    {atomic, ok}.
+
+remove_user(LUser, LServer) ->
+    {atomic, ejabberd_riak:delete_by_index(offline_msg,
+                                           <<"us">>, {LUser, LServer})}.
+
+read_message_headers(LUser, LServer) ->
+    case ejabberd_riak:get_by_index(
+           offline_msg, offline_msg_schema(),
+	   <<"us">>, {LUser, LServer}) of
+        {ok, Rs} ->
+	    Hdrs = lists:map(
+		     fun(#offline_msg{from = From, to = To, packet = Pkt,
+				      timestamp = TS}) ->
+			     Seq = now_to_integer(TS),
+			     NewPkt = jlib:add_delay_info(
+					Pkt, LServer, TS, <<"Offline Storage">>),
+			     {Seq, From, To, NewPkt}
+		     end, Rs),
+	    lists:keysort(1, Hdrs);
+	_Err ->
+	    []
+    end.
+
+read_message(_LUser, _LServer, I) ->
+    TS = integer_to_now(I),
+    case ejabberd_riak:get(offline_msg, offline_msg_schema(), TS) of
+	{ok, Msg} ->
+	    {ok, Msg};
+	_ ->
+	    error
+    end.
+
+remove_message(_LUser, _LServer, I) ->
+    TS = integer_to_now(I),
+    ejabberd_riak:delete(offline_msg, TS),
+    ok.
+
+read_all_messages(LUser, LServer) ->
+    case ejabberd_riak:get_by_index(
+           offline_msg, offline_msg_schema(),
+	   <<"us">>, {LUser, LServer}) of
+        {ok, Rs} ->
+            lists:keysort(#offline_msg.timestamp, Rs);
+        _Err ->
+            []
+    end.
+
+remove_all_messages(LUser, LServer) ->
+    Res = ejabberd_riak:delete_by_index(offline_msg,
+                                        <<"us">>, {LUser, LServer}),
+    {atomic, Res}.
+
+count_messages(LUser, LServer) ->
+    case ejabberd_riak:count_by_index(
+           offline_msg, <<"us">>, {LUser, LServer}) of
+        {ok, Res} ->
+            Res;
+        _ ->
+            0
+    end.
+
+import(_LServer, #offline_msg{us = US, timestamp = TS} = M) ->
+    ejabberd_riak:put(M, offline_msg_schema(),
+		      [{i, TS}, {'2i', [{<<"us">>, US}]}]).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+offline_msg_schema() ->
+    {record_info(fields, offline_msg), #offline_msg{}}.
+
+now_to_integer({MS, S, US}) ->
+    (MS * 1000000 + S) * 1000000 + US.
+
+integer_to_now(Int) ->
+    Secs = Int div 1000000,
+    USec = Int rem 1000000,
+    MSec = Secs div 1000000,
+    Sec = Secs rem 1000000,
+    {MSec, Sec, USec}.
diff --git a/src/mod_offline_sql.erl b/src/mod_offline_sql.erl
new file mode 100644
index 00000000..37b90163
--- /dev/null
+++ b/src/mod_offline_sql.erl
@@ -0,0 +1,252 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 15 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_offline_sql).
+
+-compile([{parse_transform, ejabberd_sql_pt}]).
+
+-behaviour(mod_offline).
+
+-export([init/2, store_messages/5, pop_messages/2, remove_expired_messages/1,
+	 remove_old_messages/2, remove_user/2, read_message_headers/2,
+	 read_message/3, remove_message/3, read_all_messages/2,
+	 remove_all_messages/2, count_messages/2, import/1, import/2,
+	 export/1]).
+
+-include("jlib.hrl").
+-include("mod_offline.hrl").
+-include("logger.hrl").
+-include("ejabberd_sql_pt.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+store_messages(Host, {User, _Server}, Msgs, Len, MaxOfflineMsgs) ->
+    Count = if MaxOfflineMsgs =/= infinity ->
+		    Len + count_messages(User, Host);
+	       true -> 0
+	    end,
+    if Count > MaxOfflineMsgs -> {atomic, discard};
+       true ->
+	    Query = lists:map(
+		      fun(M) ->
+			      Username =
+				  ejabberd_odbc:escape((M#offline_msg.to)#jid.luser),
+			      From = M#offline_msg.from,
+			      To = M#offline_msg.to,
+			      Packet =
+				  jlib:replace_from_to(From, To,
+						       M#offline_msg.packet),
+			      NewPacket =
+				  jlib:add_delay_info(Packet, Host,
+						      M#offline_msg.timestamp,
+						      <<"Offline Storage">>),
+			      XML =
+				  ejabberd_odbc:escape(fxml:element_to_binary(NewPacket)),
+				     odbc_queries:add_spool_sql(Username, XML)
+		      end,
+		      Msgs),
+	    odbc_queries:add_spool(Host, Query)
+    end.
+
+pop_messages(LUser, LServer) ->
+    case odbc_queries:get_and_del_spool_msg_t(LServer, LUser) of
+	{atomic, {selected, Rs}} ->
+	    {ok, lists:flatmap(
+		   fun({_, XML}) ->
+			   case xml_to_offline_msg(XML) of
+			       {ok, Msg} ->
+				   [Msg];
+			       _Err ->
+				   []
+			   end
+		   end, Rs)};
+	Err ->
+	    {error, Err}
+    end.
+
+remove_expired_messages(_LServer) ->
+    %% TODO
+    {atomic, ok}.
+
+remove_old_messages(Days, LServer) ->
+    case catch ejabberd_odbc:sql_query(
+		 LServer,
+		 [<<"DELETE FROM spool"
+		   " WHERE created_at < "
+		   "DATE_SUB(CURDATE(), INTERVAL ">>,
+		  integer_to_list(Days), <<" DAY);">>]) of
+	{updated, N} ->
+	    ?INFO_MSG("~p message(s) deleted from offline spool", [N]);
+	_Error ->
+	    ?ERROR_MSG("Cannot delete message in offline spool: ~p", [_Error])
+    end,
+    {atomic, ok}.
+
+remove_user(LUser, LServer) ->
+    odbc_queries:del_spool_msg(LServer, LUser).
+
+read_message_headers(LUser, LServer) ->
+    Username = ejabberd_odbc:escape(LUser),
+    case catch ejabberd_odbc:sql_query(
+		 LServer, [<<"select xml, seq from spool where username ='">>,
+			   Username, <<"' order by seq;">>]) of
+	{selected, [<<"xml">>, <<"seq">>], Rows} ->
+	    lists:flatmap(
+	      fun([XML, Seq]) ->
+		      case xml_to_offline_msg(XML) of
+			  {ok, #offline_msg{from = From,
+					    to = To,
+					    packet = El}} ->
+			      Seq0 = binary_to_integer(Seq),
+			      [{Seq0, From, To, El}];
+			  _ ->
+			      []
+		      end
+	      end, Rows);
+	_Err ->
+	    []
+    end.
+
+read_message(LUser, LServer, Seq) ->
+    Username = ejabberd_odbc:escape(LUser),
+    SSeq = ejabberd_odbc:escape(integer_to_binary(Seq)),
+    case ejabberd_odbc:sql_query(
+	   LServer,
+	   [<<"select xml from spool  where username='">>, Username,
+	    <<"'  and seq='">>, SSeq, <<"';">>]) of
+	{selected, [<<"xml">>], [[RawXML]|_]} ->
+	    case xml_to_offline_msg(RawXML) of
+		{ok, Msg} ->
+		    {ok, Msg};
+		_ ->
+		    error
+	    end;
+	_ ->
+	    error
+    end.
+
+remove_message(LUser, LServer, Seq) ->
+    Username = ejabberd_odbc:escape(LUser),
+    SSeq = ejabberd_odbc:escape(integer_to_binary(Seq)),
+    ejabberd_odbc:sql_query(
+      LServer,
+      [<<"delete from spool  where username='">>, Username,
+       <<"'  and seq='">>, SSeq, <<"';">>]),
+    ok.
+
+read_all_messages(LUser, LServer) ->
+    case catch ejabberd_odbc:sql_query(
+                 LServer,
+                 ?SQL("select @(xml)s from spool where "
+                      "username=%(LUser)s order by seq")) of
+        {selected, Rs} ->
+            lists:flatmap(
+              fun({XML}) ->
+		      case xml_to_offline_msg(XML) of
+			  {ok, Msg} -> [Msg];
+			  _ -> []
+		      end
+              end, Rs);
+        _ ->
+	    []
+    end.
+
+remove_all_messages(LUser, LServer) ->
+    odbc_queries:del_spool_msg(LServer, LUser),
+    {atomic, ok}.
+
+count_messages(LUser, LServer) ->
+    case catch ejabberd_odbc:sql_query(
+                 LServer,
+                 ?SQL("select @(count(*))d from spool "
+                      "where username=%(LUser)s")) of
+        {selected, [{Res}]} ->
+            Res;
+        _ -> 0
+    end.
+
+export(_Server) ->
+    [{offline_msg,
+      fun(Host, #offline_msg{us = {LUser, LServer},
+                             timestamp = TimeStamp, from = From, to = To,
+                             packet = Packet})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              Packet1 = jlib:replace_from_to(From, To, Packet),
+              Packet2 = jlib:add_delay_info(Packet1, LServer, TimeStamp,
+                                            <<"Offline Storage">>),
+              XML = ejabberd_odbc:escape(fxml:element_to_binary(Packet2)),
+              [[<<"delete from spool where username='">>, Username, <<"';">>],
+               [<<"insert into spool(username, xml) values ('">>,
+                Username, <<"', '">>, XML, <<"');">>]];
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select username, xml from spool;">>,
+      fun([LUser, XML]) ->
+              El = #xmlel{} = fxml_stream:parse_element(XML),
+              From = #jid{} = jid:from_string(
+                                fxml:get_attr_s(<<"from">>, El#xmlel.attrs)),
+              To = #jid{} = jid:from_string(
+                              fxml:get_attr_s(<<"to">>, El#xmlel.attrs)),
+              Stamp = fxml:get_path_s(El, [{elem, <<"delay">>},
+                                          {attr, <<"stamp">>}]),
+              TS = case jlib:datetime_string_to_timestamp(Stamp) of
+                       {_, _, _} = Now ->
+                           Now;
+                       undefined ->
+                           p1_time_compat:timestamp()
+                   end,
+              Expire = mod_offline:find_x_expire(TS, El#xmlel.children),
+              #offline_msg{us = {LUser, LServer},
+                           from = From, to = To,
+			   packet = El,
+                           timestamp = TS, expire = Expire}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+xml_to_offline_msg(XML) ->
+    case fxml_stream:parse_element(XML) of
+	#xmlel{} = El ->
+	    el_to_offline_msg(El);
+	Err ->
+	    ?ERROR_MSG("got ~p when parsing XML packet ~s",
+		       [Err, XML]),
+	    Err
+    end.
+
+el_to_offline_msg(El) ->
+    To_s = fxml:get_tag_attr_s(<<"to">>, El),
+    From_s = fxml:get_tag_attr_s(<<"from">>, El),
+    To = jid:from_string(To_s),
+    From = jid:from_string(From_s),
+    if To == error ->
+	    ?ERROR_MSG("failed to get 'to' JID from offline XML ~p", [El]),
+	    {error, bad_jid_to};
+       From == error ->
+	    ?ERROR_MSG("failed to get 'from' JID from offline XML ~p", [El]),
+	    {error, bad_jid_from};
+       true ->
+	    {ok, #offline_msg{us = {To#jid.luser, To#jid.lserver},
+			      from = From,
+			      to = To,
+			      timestamp = undefined,
+			      expire = undefined,
+			      packet = El}}
+    end.
diff --git a/src/mod_privacy.erl b/src/mod_privacy.erl
index ea36fed2..413dcb52 100644
--- a/src/mod_privacy.erl
+++ b/src/mod_privacy.erl
@@ -33,19 +33,10 @@
 
 -export([start/2, stop/1, process_iq/3, export/1, import/1,
 	 process_iq_set/4, process_iq_get/5, get_user_list/3,
-	 check_packet/6, remove_user/2, item_to_raw/1,
-	 raw_to_item/1, is_list_needdb/1, updated_list/3,
+	 check_packet/6, remove_user/2,
+	 is_list_needdb/1, updated_list/3,
          item_to_xml/1, get_user_lists/2, import/3,
-	 set_privacy_list/1]).
-
--export([sql_add_privacy_list/2,
-	 sql_get_default_privacy_list/2,
-	 sql_get_default_privacy_list_t/1,
-	 sql_get_privacy_list_data/3,
-	 sql_get_privacy_list_data_by_id_t/1,
-	 sql_get_privacy_list_id_t/2,
-	 sql_set_default_privacy_list/2, sql_set_privacy_list/2,
-	 privacy_schema/0, mod_opt_type/1]).
+	 set_privacy_list/1, mod_opt_type/1]).
 
 -include("ejabberd.hrl").
 -include("logger.hrl").
@@ -54,20 +45,24 @@
 
 -include("mod_privacy.hrl").
 
-privacy_schema() ->
-    {record_info(fields, privacy), #privacy{}}.
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #privacy{}) -> ok | pass.
+-callback process_lists_get(binary(), binary()) -> {none | binary(), [xmlel()]} | error.
+-callback process_list_get(binary(), binary(), binary()) -> [listitem()] | error | not_found.
+-callback process_default_set(binary(), binary(), {value, binary()} | false) -> {atomic, any()}.
+-callback process_active_set(binary(), binary(), binary()) -> [listitem()] | error.
+-callback remove_privacy_list(binary(), binary(), binary()) -> {atomic, any()}.
+-callback set_privacy_list(#privacy{}) -> any().
+-callback set_privacy_list(binary(), binary(), binary(), [listitem()]) -> {atomic, any()}.
+-callback get_user_list(binary(), binary()) -> {none | binary(), [listitem()]}.
+-callback get_user_lists(binary(), binary()) -> {ok, #privacy{}} | error.
+-callback remove_user(binary(), binary()) -> {atomic, any()}.
 
 start(Host, Opts) ->
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
                              one_queue),
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(privacy,
-			      [{disc_copies, [node()]},
-			       {attributes, record_info(fields, privacy)}]),
-	  update_table();
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     mod_disco:register_feature(Host, ?NS_PRIVACY),
     ejabberd_hooks:add(privacy_iq_get, Host, ?MODULE,
 		       process_iq_get, 50),
@@ -124,9 +119,8 @@ process_iq_get(_, From, _To, #iq{lang = Lang, sub_el = SubEl},
     end.
 
 process_lists_get(LUser, LServer, Active, Lang) ->
-    case process_lists_get_db(LUser, LServer, Active,
-			   gen_mod:db_type(LServer, ?MODULE))
-	of
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:process_lists_get(LUser, LServer) of
       error -> {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       {_Default, []} ->
 	  {result,
@@ -153,57 +147,9 @@ process_lists_get(LUser, LServer, Active, Lang) ->
 		   children = ADItems}]}
     end.
 
-process_lists_get_db(LUser, LServer, _Active, mnesia) ->
-    case catch mnesia:dirty_read(privacy, {LUser, LServer})
-	of
-      {'EXIT', _Reason} -> error;
-      [] -> {none, []};
-      [#privacy{default = Default, lists = Lists}] ->
-	  LItems = lists:map(fun ({N, _}) ->
-				     #xmlel{name = <<"list">>,
-					    attrs = [{<<"name">>, N}],
-					    children = []}
-			     end,
-			     Lists),
-	  {Default, LItems}
-    end;
-process_lists_get_db(LUser, LServer, _Active, riak) ->
-    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-        {ok, #privacy{default = Default, lists = Lists}} ->
-            LItems = lists:map(fun ({N, _}) ->
-                                       #xmlel{name = <<"list">>,
-                                              attrs = [{<<"name">>, N}],
-                                              children = []}
-                               end,
-                               Lists),
-            {Default, LItems};
-        {error, notfound} ->
-            {none, []};
-        {error, _} ->
-            error
-    end;
-process_lists_get_db(LUser, LServer, _Active, odbc) ->
-    Default = case catch sql_get_default_privacy_list(LUser, LServer) of
-		{selected, []} -> none;
-		{selected, [{DefName}]} -> DefName;
-		_ -> none
-	      end,
-    case catch sql_get_privacy_list_names(LUser, LServer) of
-      {selected, Names} ->
-	  LItems = lists:map(fun ({N}) ->
-				     #xmlel{name = <<"list">>,
-					    attrs = [{<<"name">>, N}],
-					    children = []}
-			     end,
-			     Names),
-	  {Default, LItems};
-      _ -> error
-    end.
-
 process_list_get(LUser, LServer, {value, Name}, Lang) ->
-    case process_list_get_db(LUser, LServer, Name,
-			  gen_mod:db_type(LServer, ?MODULE))
-	of
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:process_list_get(LUser, LServer, Name) of
       error -> {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       not_found -> {error, ?ERR_ITEM_NOT_FOUND};
       Items ->
@@ -218,41 +164,6 @@ process_list_get(LUser, LServer, {value, Name}, Lang) ->
 process_list_get(_LUser, _LServer, false, _Lang) ->
     {error, ?ERR_BAD_REQUEST}.
 
-process_list_get_db(LUser, LServer, Name, mnesia) ->
-    case catch mnesia:dirty_read(privacy, {LUser, LServer})
-	of
-      {'EXIT', _Reason} -> error;
-      [] -> not_found;
-      [#privacy{lists = Lists}] ->
-	  case lists:keysearch(Name, 1, Lists) of
-	    {value, {_, List}} -> List;
-	    _ -> not_found
-	  end
-    end;
-process_list_get_db(LUser, LServer, Name, riak) ->
-    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-        {ok, #privacy{lists = Lists}} ->
-            case lists:keysearch(Name, 1, Lists) of
-                {value, {_, List}} -> List;
-                _ -> not_found
-            end;
-        {error, notfound} ->
-            not_found;
-        {error, _} ->
-            error
-    end;
-process_list_get_db(LUser, LServer, Name, odbc) ->
-    case catch sql_get_privacy_list_id(LUser, LServer, Name) of
-      {selected, []} -> not_found;
-      {selected, [{ID}]} ->
-	  case catch sql_get_privacy_list_data_by_id(ID, LServer) of
-	    {selected, RItems} ->
-		lists:flatmap(fun raw_to_item/1, RItems);
-	    _ -> error
-	  end;
-      _ -> error
-    end.
-
 item_to_xml(Item) ->
     Attrs1 = [{<<"action">>,
 	       action_to_list(Item#listitem.action)},
@@ -357,9 +268,8 @@ process_iq_set(_, From, _To, #iq{lang = Lang, sub_el = SubEl}) ->
     end.
 
 process_default_set(LUser, LServer, Value, Lang) ->
-    case process_default_set_db(LUser, LServer, Value,
-			     gen_mod:db_type(LServer, ?MODULE))
-	of
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:process_default_set(LUser, LServer, Value) of
       {atomic, error} ->
 	    {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)};
       {atomic, not_found} -> {error, ?ERR_ITEM_NOT_FOUND};
@@ -367,79 +277,9 @@ process_default_set(LUser, LServer, Value, Lang) ->
       _ -> {error, ?ERR_INTERNAL_SERVER_ERROR}
     end.
 
-process_default_set_db(LUser, LServer, {value, Name},
-		    mnesia) ->
-    F = fun () ->
-		case mnesia:read({privacy, {LUser, LServer}}) of
-		  [] -> not_found;
-		  [#privacy{lists = Lists} = P] ->
-		      case lists:keymember(Name, 1, Lists) of
-			true ->
-			    mnesia:write(P#privacy{default = Name,
-						   lists = Lists}),
-			    ok;
-			false -> not_found
-		      end
-		end
-	end,
-    mnesia:transaction(F);
-process_default_set_db(LUser, LServer, {value, Name}, riak) ->
-    {atomic,
-     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-         {ok, #privacy{lists = Lists} = P} ->
-             case lists:keymember(Name, 1, Lists) of
-                 true ->
-                     ejabberd_riak:put(P#privacy{default = Name,
-                                                 lists = Lists},
-				       privacy_schema());
-                 false ->
-                     not_found
-             end;
-         {error, _} ->
-             not_found
-     end};
-process_default_set_db(LUser, LServer, {value, Name},
-		    odbc) ->
-    F = fun () ->
-		case sql_get_privacy_list_names_t(LUser) of
-		  {selected, []} -> not_found;
-		  {selected, Names} ->
-		      case lists:member({Name}, Names) of
-			true -> sql_set_default_privacy_list(LUser, Name), ok;
-			false -> not_found
-		      end
-		end
-	end,
-    odbc_queries:sql_transaction(LServer, F);
-process_default_set_db(LUser, LServer, false, mnesia) ->
-    F = fun () ->
-		case mnesia:read({privacy, {LUser, LServer}}) of
-		  [] -> ok;
-		  [R] -> mnesia:write(R#privacy{default = none})
-		end
-	end,
-    mnesia:transaction(F);
-process_default_set_db(LUser, LServer, false, riak) ->
-    {atomic,
-     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-         {ok, R} ->
-             ejabberd_riak:put(R#privacy{default = none}, privacy_schema());
-         {error, _} ->
-             ok
-     end};
-process_default_set_db(LUser, LServer, false, odbc) ->
-    case catch sql_unset_default_privacy_list(LUser,
-					      LServer)
-	of
-      {'EXIT', _Reason} -> {atomic, error};
-      {error, _Reason} -> {atomic, error};
-      _ -> {atomic, ok}
-    end.
-
 process_active_set(LUser, LServer, {value, Name}) ->
-    case process_active_set(LUser, LServer, Name,
-			    gen_mod:db_type(LServer, ?MODULE))
-	of
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    case Mod:process_active_set(LUser, LServer, Name) of
       error -> {error, ?ERR_ITEM_NOT_FOUND};
       Items ->
 	  NeedDb = is_list_needdb(Items),
@@ -449,157 +289,16 @@ process_active_set(LUser, LServer, {value, Name}) ->
 process_active_set(_LUser, _LServer, false) ->
     {result, [], #userlist{}}.
 
-process_active_set(LUser, LServer, Name, mnesia) ->
-    case catch mnesia:dirty_read(privacy, {LUser, LServer})
-	of
-      [] -> error;
-      [#privacy{lists = Lists}] ->
-	  case lists:keysearch(Name, 1, Lists) of
-	    {value, {_, List}} -> List;
-	    false -> error
-	  end
-    end;
-process_active_set(LUser, LServer, Name, riak) ->
-    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-        {ok, #privacy{lists = Lists}} ->
-            case lists:keysearch(Name, 1, Lists) of
-                {value, {_, List}} -> List;
-                false -> error
-            end;
-        {error, _} ->
-            error
-    end;
-process_active_set(LUser, LServer, Name, odbc) ->
-    case catch sql_get_privacy_list_id(LUser, LServer, Name) of
-      {selected, []} -> error;
-      {selected, [{ID}]} ->
-	  case catch sql_get_privacy_list_data_by_id(ID, LServer) of
-	    {selected, RItems} ->
-		lists:flatmap(fun raw_to_item/1, RItems);
-	    _ -> error
-	  end;
-      _ -> error
-    end.
-
-remove_privacy_list(LUser, LServer, Name, mnesia) ->
-    F = fun () ->
-		case mnesia:read({privacy, {LUser, LServer}}) of
-		  [] -> ok;
-		  [#privacy{default = Default, lists = Lists} = P] ->
-		      if Name == Default -> conflict;
-			 true ->
-			     NewLists = lists:keydelete(Name, 1, Lists),
-			     mnesia:write(P#privacy{lists = NewLists})
-		      end
-		end
-	end,
-    mnesia:transaction(F);
-remove_privacy_list(LUser, LServer, Name, riak) ->
-    {atomic,
-     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-         {ok, #privacy{default = Default, lists = Lists} = P} ->
-             if Name == Default ->
-                     conflict;
-                true ->
-                     NewLists = lists:keydelete(Name, 1, Lists),
-                     ejabberd_riak:put(P#privacy{lists = NewLists},
-				       privacy_schema())
-             end;
-         {error, _} ->
-             ok
-     end};
-remove_privacy_list(LUser, LServer, Name, odbc) ->
-    F = fun () ->
-		case sql_get_default_privacy_list_t(LUser) of
-		  {selected, []} ->
-		      sql_remove_privacy_list(LUser, Name), ok;
-		  {selected, [{Default}]} ->
-		      if Name == Default -> conflict;
-			 true -> sql_remove_privacy_list(LUser, Name), ok
-		      end
-		end
-	end,
-    odbc_queries:sql_transaction(LServer, F).
-
 set_privacy_list(#privacy{us = {_, LServer}} = Privacy) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    set_privacy_list(Privacy, DBType).
-
-set_privacy_list(Privacy, mnesia) ->
-    mnesia:dirty_write(Privacy);
-set_privacy_list(Privacy, riak) ->
-    ejabberd_riak:put(Privacy, privacy_schema());
-set_privacy_list(#privacy{us = {LUser, LServer},
-			  default = Default,
-			  lists = Lists}, odbc) ->
-    F = fun() ->
-		lists:foreach(
-		  fun({Name, List}) ->
-			  sql_add_privacy_list(LUser, Name),
-			  {selected, [<<"id">>], [[I]]} =
-			      sql_get_privacy_list_id_t(LUser, Name),
-			  RItems = lists:map(fun item_to_raw/1, List),
-			  sql_set_privacy_list(I, RItems),
-			  if is_binary(Default) ->
-				  sql_set_default_privacy_list(LUser, Default),
-				  ok;
-			     true ->
-				  ok
-			  end
-		  end, Lists)
-	end,
-    odbc_queries:sql_transaction(LServer, F).
-
-set_privacy_list(LUser, LServer, Name, List, mnesia) ->
-    F = fun () ->
-		case mnesia:wread({privacy, {LUser, LServer}}) of
-		  [] ->
-		      NewLists = [{Name, List}],
-		      mnesia:write(#privacy{us = {LUser, LServer},
-					    lists = NewLists});
-		  [#privacy{lists = Lists} = P] ->
-		      NewLists1 = lists:keydelete(Name, 1, Lists),
-		      NewLists = [{Name, List} | NewLists1],
-		      mnesia:write(P#privacy{lists = NewLists})
-		end
-	end,
-    mnesia:transaction(F);
-set_privacy_list(LUser, LServer, Name, List, riak) ->
-    {atomic,
-     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-         {ok, #privacy{lists = Lists} = P} ->
-             NewLists1 = lists:keydelete(Name, 1, Lists),
-             NewLists = [{Name, List} | NewLists1],
-             ejabberd_riak:put(P#privacy{lists = NewLists}, privacy_schema());
-         {error, _} ->
-             NewLists = [{Name, List}],
-             ejabberd_riak:put(#privacy{us = {LUser, LServer},
-                                        lists = NewLists},
-			       privacy_schema())
-     end};
-set_privacy_list(LUser, LServer, Name, List, odbc) ->
-    RItems = lists:map(fun item_to_raw/1, List),
-    F = fun () ->
-		ID = case sql_get_privacy_list_id_t(LUser, Name) of
-                         {selected, []} ->
-			   sql_add_privacy_list(LUser, Name),
-			   {selected, [{I}]} =
-			       sql_get_privacy_list_id_t(LUser, Name),
-			   I;
-		       {selected, [{I}]} -> I
-		     end,
-		sql_set_privacy_list(ID, RItems),
-		ok
-	end,
-    odbc_queries:sql_transaction(LServer, F).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:set_privacy_list(Privacy).
 
 process_list_set(LUser, LServer, {value, Name}, Els, Lang) ->
     case parse_items(Els) of
       false -> {error, ?ERR_BAD_REQUEST};
       remove ->
-	  case remove_privacy_list(LUser, LServer, Name,
-				   gen_mod:db_type(LServer, ?MODULE))
-	      of
+	  Mod = gen_mod:db_mod(LServer, ?MODULE),
+	  case Mod:remove_privacy_list(LUser, LServer, Name) of
 	    {atomic, conflict} ->
 		  Txt = <<"Cannot remove default list">>,
 		  {error, ?ERRT_CONFLICT(Lang, Txt)};
@@ -615,9 +314,8 @@ process_list_set(LUser, LServer, {value, Name}, Els, Lang) ->
 	    _ -> {error, ?ERRT_INTERNAL_SERVER_ERROR(Lang, <<"Database failure">>)}
 	  end;
       List ->
-	  case set_privacy_list(LUser, LServer, Name, List,
-				gen_mod:db_type(LServer, ?MODULE))
-	      of
+	  Mod = gen_mod:db_mod(LServer, ?MODULE),
+	  case Mod:set_privacy_list(LUser, LServer, Name, List) of
 	    {atomic, ok} ->
 		NeedDb = is_list_needdb(List),
 		ejabberd_sm:route(jid:make(LUser, LServer,
@@ -737,105 +435,20 @@ is_list_needdb(Items) ->
 	      end,
 	      Items).
 
-get_user_list(Acc, User, Server) ->
+get_user_list(_Acc, User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    {Default, Items} = get_user_list(Acc, LUser, LServer,
-				     gen_mod:db_type(LServer, ?MODULE)),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    {Default, Items} = Mod:get_user_list(LUser, LServer),
     NeedDb = is_list_needdb(Items),
     #userlist{name = Default, list = Items,
 	      needdb = NeedDb}.
 
-get_user_list(_, LUser, LServer, mnesia) ->
-    case catch mnesia:dirty_read(privacy, {LUser, LServer})
-	of
-      [] -> {none, []};
-      [#privacy{default = Default, lists = Lists}] ->
-	  case Default of
-	    none -> {none, []};
-	    _ ->
-		case lists:keysearch(Default, 1, Lists) of
-		  {value, {_, List}} -> {Default, List};
-		  _ -> {none, []}
-		end
-	  end;
-      _ -> {none, []}
-    end;
-get_user_list(_, LUser, LServer, riak) ->
-    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-        {ok, #privacy{default = Default, lists = Lists}} ->
-            case Default of
-                none -> {none, []};
-                _ ->
-                    case lists:keysearch(Default, 1, Lists) of
-                        {value, {_, List}} -> {Default, List};
-                        _ -> {none, []}
-                    end
-            end;
-        {error, _} ->
-            {none, []}
-    end;
-get_user_list(_, LUser, LServer, odbc) ->
-    case catch sql_get_default_privacy_list(LUser, LServer)
-	of
-      {selected, []} -> {none, []};
-      {selected, [{Default}]} ->
-	  case catch sql_get_privacy_list_data(LUser, LServer,
-					       Default) of
-              {selected, RItems} ->
-		{Default, lists:flatmap(fun raw_to_item/1, RItems)};
-	    _ -> {none, []}
-	  end;
-      _ -> {none, []}
-    end.
-
 get_user_lists(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    get_user_lists(LUser, LServer, gen_mod:db_type(LServer, ?MODULE)).
-
-get_user_lists(LUser, LServer, mnesia) ->
-    case catch mnesia:dirty_read(privacy, {LUser, LServer}) of
-        [#privacy{} = P] ->
-            {ok, P};
-        _ ->
-            error
-    end;
-get_user_lists(LUser, LServer, riak) ->
-    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
-        {ok, #privacy{} = P} ->
-            {ok, P};
-        {error, _} ->
-            error
-    end;
-get_user_lists(LUser, LServer, odbc) ->
-    Default = case catch sql_get_default_privacy_list(LUser, LServer) of
-                  {selected, []} ->
-                      none;
-                  {selected, [{DefName}]} ->
-                      DefName;
-                  _ ->
-                      none
-	      end,
-    case catch sql_get_privacy_list_names(LUser, LServer) of
-        {selected, Names} ->
-            Lists =
-                lists:flatmap(
-                  fun({Name}) ->
-                          case catch sql_get_privacy_list_data(
-                                       LUser, LServer, Name) of
-                              {selected, RItems} ->
-                                  [{Name, lists:flatmap(fun raw_to_item/1, RItems)}];
-                              _ ->
-                                  []
-                          end
-                  end, Names),
-            {ok, #privacy{default = Default,
-                          us = {LUser, LServer},
-                          lists = Lists}};
-        _ ->
-            error
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_user_lists(LUser, LServer).
 
 %% From is the sender, To is the destination.
 %% If Dir = out, User@Server is the sender account (From).
@@ -959,17 +572,8 @@ is_type_match(Type, Value, JID, Subscription, Groups) ->
 remove_user(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    remove_user(LUser, LServer,
-		gen_mod:db_type(LServer, ?MODULE)).
-
-remove_user(LUser, LServer, mnesia) ->
-    F = fun () -> mnesia:delete({privacy, {LUser, LServer}})
-	end,
-    mnesia:transaction(F);
-remove_user(LUser, LServer, riak) ->
-    {atomic, ejabberd_riak:delete(privacy, {LUser, LServer})};
-remove_user(LUser, LServer, odbc) ->
-    sql_del_privacy_lists(LUser, LServer).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_user(LUser, LServer).
 
 updated_list(_, #userlist{name = OldName} = Old,
 	     #userlist{name = NewName} = New) ->
@@ -977,250 +581,17 @@ updated_list(_, #userlist{name = OldName} = Old,
        true -> Old
     end.
 
-raw_to_item({SType, SValue, SAction, Order, MatchAll,
-	     MatchIQ, MatchMessage, MatchPresenceIn,
-	     MatchPresenceOut} = Row) ->
-    try
-        {Type, Value} = case SType of
-                            <<"n">> -> {none, none};
-                            <<"j">> ->
-                                case jid:from_string(SValue) of
-                                    #jid{} = JID ->
-                                        {jid, jid:tolower(JID)}
-                                end;
-                            <<"g">> -> {group, SValue};
-                            <<"s">> ->
-                                case SValue of
-                                    <<"none">> -> {subscription, none};
-                                    <<"both">> -> {subscription, both};
-                                    <<"from">> -> {subscription, from};
-                                    <<"to">> -> {subscription, to}
-                                end
-                        end,
-        Action = case SAction of
-                     <<"a">> -> allow;
-                     <<"d">> -> deny
-                 end,
-        [#listitem{type = Type, value = Value, action = Action,
-                   order = Order, match_all = MatchAll, match_iq = MatchIQ,
-                   match_message = MatchMessage,
-                   match_presence_in = MatchPresenceIn,
-                   match_presence_out = MatchPresenceOut}]
-    catch _:_ ->
-            ?WARNING_MSG("failed to parse row: ~p", [Row]),
-            []
-    end.
-
-item_to_raw(#listitem{type = Type, value = Value,
-		      action = Action, order = Order, match_all = MatchAll,
-		      match_iq = MatchIQ, match_message = MatchMessage,
-		      match_presence_in = MatchPresenceIn,
-		      match_presence_out = MatchPresenceOut}) ->
-    {SType, SValue} = case Type of
-			none -> {<<"n">>, <<"">>};
-			jid ->
-			    {<<"j">>,
-			     ejabberd_odbc:escape(jid:to_string(Value))};
-			group -> {<<"g">>, ejabberd_odbc:escape(Value)};
-			subscription ->
-			    case Value of
-			      none -> {<<"s">>, <<"none">>};
-			      both -> {<<"s">>, <<"both">>};
-			      from -> {<<"s">>, <<"from">>};
-			      to -> {<<"s">>, <<"to">>}
-			    end
-		      end,
-    SAction = case Action of
-		allow -> <<"a">>;
-		deny -> <<"d">>
-	      end,
-    {SType, SValue, SAction, Order, MatchAll, MatchIQ,
-     MatchMessage, MatchPresenceIn, MatchPresenceOut}.
-
-sql_get_default_privacy_list(LUser, LServer) ->
-    odbc_queries:get_default_privacy_list(LServer, LUser).
-
-sql_get_default_privacy_list_t(LUser) ->
-    odbc_queries:get_default_privacy_list_t(LUser).
-
-sql_get_privacy_list_names(LUser, LServer) ->
-    odbc_queries:get_privacy_list_names(LServer, LUser).
-
-sql_get_privacy_list_names_t(LUser) ->
-    odbc_queries:get_privacy_list_names_t(LUser).
-
-sql_get_privacy_list_id(LUser, LServer, Name) ->
-    odbc_queries:get_privacy_list_id(LServer, LUser, Name).
-
-sql_get_privacy_list_id_t(LUser, Name) ->
-    odbc_queries:get_privacy_list_id_t(LUser, Name).
-
-sql_get_privacy_list_data(LUser, LServer, Name) ->
-    odbc_queries:get_privacy_list_data(LServer, LUser, Name).
-
-sql_get_privacy_list_data_t(LUser, Name) ->
-    Username = ejabberd_odbc:escape(LUser),
-    SName = ejabberd_odbc:escape(Name),
-    odbc_queries:get_privacy_list_data_t(Username, SName).
-
-sql_get_privacy_list_data_by_id(ID, LServer) ->
-    odbc_queries:get_privacy_list_data_by_id(LServer, ID).
-
-sql_get_privacy_list_data_by_id_t(ID) ->
-    odbc_queries:get_privacy_list_data_by_id_t(ID).
-
-sql_set_default_privacy_list(LUser, Name) ->
-    odbc_queries:set_default_privacy_list(LUser, Name).
-
-sql_unset_default_privacy_list(LUser, LServer) ->
-    odbc_queries:unset_default_privacy_list(LServer, LUser).
-
-sql_remove_privacy_list(LUser, Name) ->
-    odbc_queries:remove_privacy_list(LUser, Name).
-
-sql_add_privacy_list(LUser, Name) ->
-    odbc_queries:add_privacy_list(LUser, Name).
-
-sql_set_privacy_list(ID, RItems) ->
-    odbc_queries:set_privacy_list(ID, RItems).
-
-sql_del_privacy_lists(LUser, LServer) ->
-    odbc_queries:del_privacy_lists(LServer, LUser).
-
-update_table() ->
-    Fields = record_info(fields, privacy),
-    case mnesia:table_info(privacy, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            privacy, Fields, set,
-            fun(#privacy{us = {U, _}}) -> U end,
-            fun(#privacy{us = {U, S}, default = Def, lists = Lists} = R) ->
-                    NewLists =
-                        lists:map(
-                          fun({Name, Ls}) ->
-                                  NewLs =
-                                      lists:map(
-                                        fun(#listitem{value = Val} = L) ->
-                                                NewVal =
-                                                    case Val of
-                                                        {LU, LS, LR} ->
-                                                            {iolist_to_binary(LU),
-                                                             iolist_to_binary(LS),
-                                                             iolist_to_binary(LR)};
-                                                        none -> none;
-                                                        both -> both;
-                                                        from -> from;
-                                                        to -> to;
-                                                        _ -> iolist_to_binary(Val)
-                                                    end,
-                                                L#listitem{value = NewVal}
-                                        end, Ls),
-                                  {iolist_to_binary(Name), NewLs}
-                          end, Lists),
-                    NewDef = case Def of
-                                 none -> none;
-                                 _ -> iolist_to_binary(Def)
-                             end,
-                    NewUS = {iolist_to_binary(U), iolist_to_binary(S)},
-                    R#privacy{us = NewUS, default = NewDef,
-                              lists = NewLists}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating privacy table", []),
-	  mnesia:transform_table(privacy, ignore, Fields)
-    end.
-
-export(Server) ->
-    case catch ejabberd_odbc:sql_query(jid:nameprep(Server),
-				 [<<"select id from privacy_list order by "
-				    "id desc limit 1;">>]) of
-        {selected, [<<"id">>], [[I]]} ->
-            put(id, jlib:binary_to_integer(I));
-        _ ->
-            put(id, 0)
-    end,
-    [{privacy,
-      fun(Host, #privacy{us = {LUser, LServer}, lists = Lists,
-                         default = Default})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              if Default /= none ->
-                      SDefault = ejabberd_odbc:escape(Default),
-                      [[<<"delete from privacy_default_list where ">>,
-                        <<"username='">>, Username, <<"';">>],
-                       [<<"insert into privacy_default_list(username, "
-                          "name) ">>,
-                        <<"values ('">>, Username, <<"', '">>,
-                        SDefault, <<"');">>]];
-                 true ->
-                      []
-              end ++
-                  lists:flatmap(
-                    fun({Name, List}) ->
-                            SName = ejabberd_odbc:escape(Name),
-                            RItems = lists:map(fun item_to_raw/1, List),
-                            ID = jlib:integer_to_binary(get_id()),
-                            [[<<"delete from privacy_list where username='">>,
-                              Username, <<"' and name='">>,
-                              SName, <<"';">>],
-                             [<<"insert into privacy_list(username, "
-                                "name, id) values ('">>,
-                              Username, <<"', '">>, SName,
-                              <<"', '">>, ID, <<"');">>],
-                             [<<"delete from privacy_list_data where "
-                                "id='">>, ID, <<"';">>]] ++
-                                [[<<"insert into privacy_list_data(id, t, "
-                                    "value, action, ord, match_all, match_iq, "
-                                    "match_message, match_presence_in, "
-                                    "match_presence_out) values ('">>,
-                                  ID, <<"', '">>, str:join(Items, <<"', '">>),
-                                  <<"');">>] || Items <- RItems]
-                    end,
-                    Lists);
-         (_Host, _R) ->
-              []
-      end}].
-
-get_id() ->
-    ID = get(id),
-    put(id, ID + 1),
-    ID + 1.
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select username from privacy_list;">>,
-      fun([LUser]) ->
-              Default = case sql_get_default_privacy_list_t(LUser) of
-                            {selected, [<<"name">>], []} ->
-                                none;
-                            {selected, [<<"name">>], [[DefName]]} ->
-                                DefName;
-                            _ ->
-                                none
-                        end,
-              {selected, [<<"name">>], Names} =
-                  sql_get_privacy_list_names_t(LUser),
-              Lists = lists:flatmap(
-                        fun([Name]) ->
-                                case sql_get_privacy_list_data_t(LUser, Name) of
-                                    {selected, _, RItems} ->
-                                        [{Name,
-                                          lists:map(fun raw_to_item/1,
-                                                    RItems)}];
-                                    _ ->
-                                        []
-                                end
-                        end, Names),
-              #privacy{default = Default,
-                       us = {LUser, LServer},
-                       lists = Lists}
-      end}].
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
 
-import(_LServer, mnesia, #privacy{} = P) ->
-    mnesia:dirty_write(P);
-import(_LServer, riak, #privacy{} = P) ->
-    ejabberd_riak:put(P, privacy_schema());
-import(_, _, _) ->
-    pass.
+import(LServer, DBType, Data) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, Data).
 
 mod_opt_type(db_type) -> fun gen_mod:v_db/1;
 mod_opt_type(iqdisc) -> fun gen_iq_handler:check_type/1;
diff --git a/src/mod_privacy_mnesia.erl b/src/mod_privacy_mnesia.erl
new file mode 100644
index 00000000..4026b7f6
--- /dev/null
+++ b/src/mod_privacy_mnesia.erl
@@ -0,0 +1,198 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_privacy_mnesia).
+
+-behaviour(mod_privacy).
+
+%% API
+-export([init/2, process_lists_get/2, process_list_get/3,
+	 process_default_set/3, process_active_set/3,
+	 remove_privacy_list/3, set_privacy_list/1,
+	 set_privacy_list/4, get_user_list/2, get_user_lists/2,
+	 remove_user/2, import/2]).
+
+-include("jlib.hrl").
+-include("mod_privacy.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(privacy,
+			[{disc_copies, [node()]},
+			 {attributes, record_info(fields, privacy)}]),
+    update_table().
+
+process_lists_get(LUser, LServer) ->
+    case catch mnesia:dirty_read(privacy, {LUser, LServer}) of
+	{'EXIT', _Reason} -> error;
+	[] -> {none, []};
+	[#privacy{default = Default, lists = Lists}] ->
+	    LItems = lists:map(fun ({N, _}) ->
+				       #xmlel{name = <<"list">>,
+					      attrs = [{<<"name">>, N}],
+					      children = []}
+			       end, Lists),
+	    {Default, LItems}
+    end.
+
+process_list_get(LUser, LServer, Name) ->
+    case catch mnesia:dirty_read(privacy, {LUser, LServer}) of
+	{'EXIT', _Reason} -> error;
+	[] -> not_found;
+	[#privacy{lists = Lists}] ->
+	    case lists:keysearch(Name, 1, Lists) of
+		{value, {_, List}} -> List;
+		_ -> not_found
+	    end
+    end.
+
+process_default_set(LUser, LServer, {value, Name}) ->
+    F = fun () ->
+		case mnesia:read({privacy, {LUser, LServer}}) of
+		    [] -> not_found;
+		    [#privacy{lists = Lists} = P] ->
+			case lists:keymember(Name, 1, Lists) of
+			    true ->
+				mnesia:write(P#privacy{default = Name,
+						       lists = Lists}),
+				ok;
+			    false -> not_found
+			end
+		end
+	end,
+    mnesia:transaction(F);
+process_default_set(LUser, LServer, false) ->
+    F = fun () ->
+		case mnesia:read({privacy, {LUser, LServer}}) of
+		    [] -> ok;
+		    [R] -> mnesia:write(R#privacy{default = none})
+		end
+	end,
+    mnesia:transaction(F).
+
+process_active_set(LUser, LServer, Name) ->
+    case catch mnesia:dirty_read(privacy, {LUser, LServer}) of
+	[] -> error;
+	[#privacy{lists = Lists}] ->
+	    case lists:keysearch(Name, 1, Lists) of
+		{value, {_, List}} -> List;
+		false -> error
+	    end
+    end.
+
+remove_privacy_list(LUser, LServer, Name) ->
+    F = fun () ->
+		case mnesia:read({privacy, {LUser, LServer}}) of
+		  [] -> ok;
+		  [#privacy{default = Default, lists = Lists} = P] ->
+		      if Name == Default -> conflict;
+			 true ->
+			     NewLists = lists:keydelete(Name, 1, Lists),
+			     mnesia:write(P#privacy{lists = NewLists})
+		      end
+		end
+	end,
+    mnesia:transaction(F).
+
+set_privacy_list(Privacy) ->
+    mnesia:dirty_write(Privacy).
+
+set_privacy_list(LUser, LServer, Name, List) ->
+    F = fun () ->
+		case mnesia:wread({privacy, {LUser, LServer}}) of
+		  [] ->
+		      NewLists = [{Name, List}],
+		      mnesia:write(#privacy{us = {LUser, LServer},
+					    lists = NewLists});
+		  [#privacy{lists = Lists} = P] ->
+		      NewLists1 = lists:keydelete(Name, 1, Lists),
+		      NewLists = [{Name, List} | NewLists1],
+		      mnesia:write(P#privacy{lists = NewLists})
+		end
+	end,
+    mnesia:transaction(F).
+
+get_user_list(LUser, LServer) ->
+    case catch mnesia:dirty_read(privacy, {LUser, LServer})
+	of
+      [] -> {none, []};
+      [#privacy{default = Default, lists = Lists}] ->
+	  case Default of
+	    none -> {none, []};
+	    _ ->
+		case lists:keysearch(Default, 1, Lists) of
+		  {value, {_, List}} -> {Default, List};
+		  _ -> {none, []}
+		end
+	  end;
+      _ -> {none, []}
+    end.
+
+get_user_lists(LUser, LServer) ->
+    case catch mnesia:dirty_read(privacy, {LUser, LServer}) of
+        [#privacy{} = P] ->
+            {ok, P};
+        _ ->
+            error
+    end.
+
+remove_user(LUser, LServer) ->
+    F = fun () -> mnesia:delete({privacy, {LUser, LServer}}) end,
+    mnesia:transaction(F).
+
+import(_LServer, #privacy{} = P) ->
+    mnesia:dirty_write(P).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_table() ->
+    Fields = record_info(fields, privacy),
+    case mnesia:table_info(privacy, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            privacy, Fields, set,
+            fun(#privacy{us = {U, _}}) -> U end,
+            fun(#privacy{us = {U, S}, default = Def, lists = Lists} = R) ->
+                    NewLists =
+                        lists:map(
+                          fun({Name, Ls}) ->
+                                  NewLs =
+                                      lists:map(
+                                        fun(#listitem{value = Val} = L) ->
+                                                NewVal =
+                                                    case Val of
+                                                        {LU, LS, LR} ->
+                                                            {iolist_to_binary(LU),
+                                                             iolist_to_binary(LS),
+                                                             iolist_to_binary(LR)};
+                                                        none -> none;
+                                                        both -> both;
+                                                        from -> from;
+                                                        to -> to;
+                                                        _ -> iolist_to_binary(Val)
+                                                    end,
+                                                L#listitem{value = NewVal}
+                                        end, Ls),
+                                  {iolist_to_binary(Name), NewLs}
+                          end, Lists),
+                    NewDef = case Def of
+                                 none -> none;
+                                 _ -> iolist_to_binary(Def)
+                             end,
+                    NewUS = {iolist_to_binary(U), iolist_to_binary(S)},
+                    R#privacy{us = NewUS, default = NewDef,
+                              lists = NewLists}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating privacy table", []),
+	  mnesia:transform_table(privacy, ignore, Fields)
+    end.
diff --git a/src/mod_privacy_riak.erl b/src/mod_privacy_riak.erl
new file mode 100644
index 00000000..0c43e74f
--- /dev/null
+++ b/src/mod_privacy_riak.erl
@@ -0,0 +1,160 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_privacy_riak).
+
+-behaviour(mod_privacy).
+
+%% API
+-export([init/2, process_lists_get/2, process_list_get/3,
+	 process_default_set/3, process_active_set/3,
+	 remove_privacy_list/3, set_privacy_list/1,
+	 set_privacy_list/4, get_user_list/2, get_user_lists/2,
+	 remove_user/2, import/2]).
+
+-export([privacy_schema/0]).
+
+-include("jlib.hrl").
+-include("mod_privacy.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+process_lists_get(LUser, LServer) ->
+    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+        {ok, #privacy{default = Default, lists = Lists}} ->
+            LItems = lists:map(fun ({N, _}) ->
+                                       #xmlel{name = <<"list">>,
+                                              attrs = [{<<"name">>, N}],
+                                              children = []}
+                               end,
+                               Lists),
+            {Default, LItems};
+        {error, notfound} ->
+            {none, []};
+        {error, _} ->
+            error
+    end.
+
+process_list_get(LUser, LServer, Name) ->
+    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+        {ok, #privacy{lists = Lists}} ->
+            case lists:keysearch(Name, 1, Lists) of
+                {value, {_, List}} -> List;
+                _ -> not_found
+            end;
+        {error, notfound} ->
+            not_found;
+        {error, _} ->
+            error
+    end.
+
+process_default_set(LUser, LServer, {value, Name}) ->
+    {atomic,
+     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+         {ok, #privacy{lists = Lists} = P} ->
+             case lists:keymember(Name, 1, Lists) of
+                 true ->
+                     ejabberd_riak:put(P#privacy{default = Name,
+                                                 lists = Lists},
+				       privacy_schema());
+                 false ->
+                     not_found
+             end;
+         {error, _} ->
+             not_found
+     end};
+process_default_set(LUser, LServer, false) ->
+    {atomic,
+     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+         {ok, R} ->
+             ejabberd_riak:put(R#privacy{default = none}, privacy_schema());
+         {error, _} ->
+             ok
+     end}.
+
+process_active_set(LUser, LServer, Name) ->
+    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+        {ok, #privacy{lists = Lists}} ->
+            case lists:keysearch(Name, 1, Lists) of
+                {value, {_, List}} -> List;
+                false -> error
+            end;
+        {error, _} ->
+            error
+    end.
+
+remove_privacy_list(LUser, LServer, Name) ->
+    {atomic,
+     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+         {ok, #privacy{default = Default, lists = Lists} = P} ->
+             if Name == Default ->
+                     conflict;
+                true ->
+                     NewLists = lists:keydelete(Name, 1, Lists),
+                     ejabberd_riak:put(P#privacy{lists = NewLists},
+				       privacy_schema())
+             end;
+         {error, _} ->
+             ok
+     end}.
+
+set_privacy_list(Privacy) ->
+    ejabberd_riak:put(Privacy, privacy_schema()).
+
+set_privacy_list(LUser, LServer, Name, List) ->
+    {atomic,
+     case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+         {ok, #privacy{lists = Lists} = P} ->
+             NewLists1 = lists:keydelete(Name, 1, Lists),
+             NewLists = [{Name, List} | NewLists1],
+             ejabberd_riak:put(P#privacy{lists = NewLists}, privacy_schema());
+         {error, _} ->
+             NewLists = [{Name, List}],
+             ejabberd_riak:put(#privacy{us = {LUser, LServer},
+                                        lists = NewLists},
+			       privacy_schema())
+     end}.
+
+get_user_list(LUser, LServer) ->
+    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+        {ok, #privacy{default = Default, lists = Lists}} ->
+            case Default of
+                none -> {none, []};
+                _ ->
+                    case lists:keysearch(Default, 1, Lists) of
+                        {value, {_, List}} -> {Default, List};
+                        _ -> {none, []}
+                    end
+            end;
+        {error, _} ->
+            {none, []}
+    end.
+
+get_user_lists(LUser, LServer) ->
+    case ejabberd_riak:get(privacy, privacy_schema(), {LUser, LServer}) of
+        {ok, #privacy{} = P} ->
+            {ok, P};
+        {error, _} ->
+            error
+    end.
+
+remove_user(LUser, LServer) ->
+    {atomic, ejabberd_riak:delete(privacy, {LUser, LServer})}.
+
+import(_LServer, #privacy{} = P) ->
+    ejabberd_riak:put(P, privacy_schema()).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+privacy_schema() ->
+    {record_info(fields, privacy), #privacy{}}.
diff --git a/src/mod_privacy_sql.erl b/src/mod_privacy_sql.erl
new file mode 100644
index 00000000..ffaf5518
--- /dev/null
+++ b/src/mod_privacy_sql.erl
@@ -0,0 +1,397 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_privacy_sql).
+
+-behaviour(mod_privacy).
+
+%% API
+-export([init/2, process_lists_get/2, process_list_get/3,
+	 process_default_set/3, process_active_set/3,
+	 remove_privacy_list/3, set_privacy_list/1,
+	 set_privacy_list/4, get_user_list/2, get_user_lists/2,
+	 remove_user/2, import/1, import/2, export/1]).
+
+-export([item_to_raw/1, raw_to_item/1,
+	 sql_add_privacy_list/2,
+	 sql_get_default_privacy_list/2,
+	 sql_get_default_privacy_list_t/1,
+	 sql_get_privacy_list_data/3,
+	 sql_get_privacy_list_data_by_id_t/1,
+	 sql_get_privacy_list_id_t/2,
+	 sql_set_default_privacy_list/2, sql_set_privacy_list/2]).
+
+-include("jlib.hrl").
+-include("mod_privacy.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+process_lists_get(LUser, LServer) ->
+    Default = case catch sql_get_default_privacy_list(LUser, LServer) of
+		{selected, []} -> none;
+		{selected, [{DefName}]} -> DefName;
+		_ -> none
+	      end,
+    case catch sql_get_privacy_list_names(LUser, LServer) of
+      {selected, Names} ->
+	  LItems = lists:map(fun ({N}) ->
+				     #xmlel{name = <<"list">>,
+					    attrs = [{<<"name">>, N}],
+					    children = []}
+			     end,
+			     Names),
+	  {Default, LItems};
+      _ -> error
+    end.
+
+process_list_get(LUser, LServer, Name) ->
+    case catch sql_get_privacy_list_id(LUser, LServer, Name) of
+      {selected, []} -> not_found;
+      {selected, [{ID}]} ->
+	  case catch sql_get_privacy_list_data_by_id(ID, LServer) of
+	    {selected, RItems} ->
+		lists:flatmap(fun raw_to_item/1, RItems);
+	    _ -> error
+	  end;
+      _ -> error
+    end.
+
+process_default_set(LUser, LServer, {value, Name}) ->
+    F = fun () ->
+		case sql_get_privacy_list_names_t(LUser) of
+		  {selected, []} -> not_found;
+		  {selected, Names} ->
+		      case lists:member({Name}, Names) of
+			true -> sql_set_default_privacy_list(LUser, Name), ok;
+			false -> not_found
+		      end
+		end
+	end,
+    odbc_queries:sql_transaction(LServer, F);
+process_default_set(LUser, LServer, false) ->
+    case catch sql_unset_default_privacy_list(LUser,
+					      LServer)
+	of
+      {'EXIT', _Reason} -> {atomic, error};
+      {error, _Reason} -> {atomic, error};
+      _ -> {atomic, ok}
+    end.
+
+process_active_set(LUser, LServer, Name) ->
+    case catch sql_get_privacy_list_id(LUser, LServer, Name) of
+      {selected, []} -> error;
+      {selected, [{ID}]} ->
+	  case catch sql_get_privacy_list_data_by_id(ID, LServer) of
+	    {selected, RItems} ->
+		lists:flatmap(fun raw_to_item/1, RItems);
+	    _ -> error
+	  end;
+      _ -> error
+    end.
+
+remove_privacy_list(LUser, LServer, Name) ->
+    F = fun () ->
+		case sql_get_default_privacy_list_t(LUser) of
+		  {selected, []} ->
+		      sql_remove_privacy_list(LUser, Name), ok;
+		  {selected, [{Default}]} ->
+		      if Name == Default -> conflict;
+			 true -> sql_remove_privacy_list(LUser, Name), ok
+		      end
+		end
+	end,
+    odbc_queries:sql_transaction(LServer, F).
+
+set_privacy_list(#privacy{us = {LUser, LServer},
+			  default = Default,
+			  lists = Lists}) ->
+    F = fun() ->
+		lists:foreach(
+		  fun({Name, List}) ->
+			  sql_add_privacy_list(LUser, Name),
+			  {selected, [<<"id">>], [[I]]} =
+			      sql_get_privacy_list_id_t(LUser, Name),
+			  RItems = lists:map(fun item_to_raw/1, List),
+			  sql_set_privacy_list(I, RItems),
+			  if is_binary(Default) ->
+				  sql_set_default_privacy_list(LUser, Default),
+				  ok;
+			     true ->
+				  ok
+			  end
+		  end, Lists)
+	end,
+    odbc_queries:sql_transaction(LServer, F).
+
+set_privacy_list(LUser, LServer, Name, List) ->
+    RItems = lists:map(fun item_to_raw/1, List),
+    F = fun () ->
+		ID = case sql_get_privacy_list_id_t(LUser, Name) of
+                         {selected, []} ->
+			   sql_add_privacy_list(LUser, Name),
+			   {selected, [{I}]} =
+			       sql_get_privacy_list_id_t(LUser, Name),
+			   I;
+		       {selected, [{I}]} -> I
+		     end,
+		sql_set_privacy_list(ID, RItems),
+		ok
+	end,
+    odbc_queries:sql_transaction(LServer, F).
+
+get_user_list(LUser, LServer) ->
+    case catch sql_get_default_privacy_list(LUser, LServer)
+	of
+      {selected, []} -> {none, []};
+      {selected, [{Default}]} ->
+	  case catch sql_get_privacy_list_data(LUser, LServer,
+					       Default) of
+              {selected, RItems} ->
+		{Default, lists:flatmap(fun raw_to_item/1, RItems)};
+	    _ -> {none, []}
+	  end;
+      _ -> {none, []}
+    end.
+
+get_user_lists(LUser, LServer) ->
+    Default = case catch sql_get_default_privacy_list(LUser, LServer) of
+                  {selected, []} ->
+                      none;
+                  {selected, [{DefName}]} ->
+                      DefName;
+                  _ ->
+                      none
+	      end,
+    case catch sql_get_privacy_list_names(LUser, LServer) of
+        {selected, Names} ->
+            Lists =
+                lists:flatmap(
+                  fun({Name}) ->
+                          case catch sql_get_privacy_list_data(
+                                       LUser, LServer, Name) of
+                              {selected, RItems} ->
+                                  [{Name, lists:flatmap(fun raw_to_item/1, RItems)}];
+                              _ ->
+                                  []
+                          end
+                  end, Names),
+            {ok, #privacy{default = Default,
+                          us = {LUser, LServer},
+                          lists = Lists}};
+        _ ->
+            error
+    end.
+
+remove_user(LUser, LServer) ->
+    sql_del_privacy_lists(LUser, LServer).
+
+export(Server) ->
+    case catch ejabberd_odbc:sql_query(jid:nameprep(Server),
+				 [<<"select id from privacy_list order by "
+				    "id desc limit 1;">>]) of
+        {selected, [<<"id">>], [[I]]} ->
+            put(id, jlib:binary_to_integer(I));
+        _ ->
+            put(id, 0)
+    end,
+    [{privacy,
+      fun(Host, #privacy{us = {LUser, LServer}, lists = Lists,
+                         default = Default})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              if Default /= none ->
+                      SDefault = ejabberd_odbc:escape(Default),
+                      [[<<"delete from privacy_default_list where ">>,
+                        <<"username='">>, Username, <<"';">>],
+                       [<<"insert into privacy_default_list(username, "
+                          "name) ">>,
+                        <<"values ('">>, Username, <<"', '">>,
+                        SDefault, <<"');">>]];
+                 true ->
+                      []
+              end ++
+                  lists:flatmap(
+                    fun({Name, List}) ->
+                            SName = ejabberd_odbc:escape(Name),
+                            RItems = lists:map(fun item_to_raw/1, List),
+                            ID = jlib:integer_to_binary(get_id()),
+                            [[<<"delete from privacy_list where username='">>,
+                              Username, <<"' and name='">>,
+                              SName, <<"';">>],
+                             [<<"insert into privacy_list(username, "
+                                "name, id) values ('">>,
+                              Username, <<"', '">>, SName,
+                              <<"', '">>, ID, <<"');">>],
+                             [<<"delete from privacy_list_data where "
+                                "id='">>, ID, <<"';">>]] ++
+                                [[<<"insert into privacy_list_data(id, t, "
+                                    "value, action, ord, match_all, match_iq, "
+                                    "match_message, match_presence_in, "
+                                    "match_presence_out) values ('">>,
+                                  ID, <<"', '">>, str:join(Items, <<"', '">>),
+                                  <<"');">>] || Items <- RItems]
+                    end,
+                    Lists);
+         (_Host, _R) ->
+              []
+      end}].
+
+get_id() ->
+    ID = get(id),
+    put(id, ID + 1),
+    ID + 1.
+
+import(LServer) ->
+    [{<<"select username from privacy_list;">>,
+      fun([LUser]) ->
+              Default = case sql_get_default_privacy_list_t(LUser) of
+                            {selected, [<<"name">>], []} ->
+                                none;
+                            {selected, [<<"name">>], [[DefName]]} ->
+                                DefName;
+                            _ ->
+                                none
+                        end,
+              {selected, [<<"name">>], Names} =
+                  sql_get_privacy_list_names_t(LUser),
+              Lists = lists:flatmap(
+                        fun([Name]) ->
+                                case sql_get_privacy_list_data_t(LUser, Name) of
+                                    {selected, _, RItems} ->
+                                        [{Name,
+                                          lists:map(fun raw_to_item/1,
+                                                    RItems)}];
+                                    _ ->
+                                        []
+                                end
+                        end, Names),
+              #privacy{default = Default,
+                       us = {LUser, LServer},
+                       lists = Lists}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+raw_to_item({SType, SValue, SAction, Order, MatchAll,
+	     MatchIQ, MatchMessage, MatchPresenceIn,
+	     MatchPresenceOut} = Row) ->
+    try
+        {Type, Value} = case SType of
+                            <<"n">> -> {none, none};
+                            <<"j">> ->
+                                case jid:from_string(SValue) of
+                                    #jid{} = JID ->
+                                        {jid, jid:tolower(JID)}
+                                end;
+                            <<"g">> -> {group, SValue};
+                            <<"s">> ->
+                                case SValue of
+                                    <<"none">> -> {subscription, none};
+                                    <<"both">> -> {subscription, both};
+                                    <<"from">> -> {subscription, from};
+                                    <<"to">> -> {subscription, to}
+                                end
+                        end,
+        Action = case SAction of
+                     <<"a">> -> allow;
+                     <<"d">> -> deny
+                 end,
+        [#listitem{type = Type, value = Value, action = Action,
+                   order = Order, match_all = MatchAll, match_iq = MatchIQ,
+                   match_message = MatchMessage,
+                   match_presence_in = MatchPresenceIn,
+                   match_presence_out = MatchPresenceOut}]
+    catch _:_ ->
+            ?WARNING_MSG("failed to parse row: ~p", [Row]),
+            []
+    end.
+
+item_to_raw(#listitem{type = Type, value = Value,
+		      action = Action, order = Order, match_all = MatchAll,
+		      match_iq = MatchIQ, match_message = MatchMessage,
+		      match_presence_in = MatchPresenceIn,
+		      match_presence_out = MatchPresenceOut}) ->
+    {SType, SValue} = case Type of
+			none -> {<<"n">>, <<"">>};
+			jid ->
+			    {<<"j">>,
+			     ejabberd_odbc:escape(jid:to_string(Value))};
+			group -> {<<"g">>, ejabberd_odbc:escape(Value)};
+			subscription ->
+			    case Value of
+			      none -> {<<"s">>, <<"none">>};
+			      both -> {<<"s">>, <<"both">>};
+			      from -> {<<"s">>, <<"from">>};
+			      to -> {<<"s">>, <<"to">>}
+			    end
+		      end,
+    SAction = case Action of
+		allow -> <<"a">>;
+		deny -> <<"d">>
+	      end,
+    {SType, SValue, SAction, Order, MatchAll, MatchIQ,
+     MatchMessage, MatchPresenceIn, MatchPresenceOut}.
+
+sql_get_default_privacy_list(LUser, LServer) ->
+    odbc_queries:get_default_privacy_list(LServer, LUser).
+
+sql_get_default_privacy_list_t(LUser) ->
+    odbc_queries:get_default_privacy_list_t(LUser).
+
+sql_get_privacy_list_names(LUser, LServer) ->
+    odbc_queries:get_privacy_list_names(LServer, LUser).
+
+sql_get_privacy_list_names_t(LUser) ->
+    odbc_queries:get_privacy_list_names_t(LUser).
+
+sql_get_privacy_list_id(LUser, LServer, Name) ->
+    odbc_queries:get_privacy_list_id(LServer, LUser, Name).
+
+sql_get_privacy_list_id_t(LUser, Name) ->
+    odbc_queries:get_privacy_list_id_t(LUser, Name).
+
+sql_get_privacy_list_data(LUser, LServer, Name) ->
+    odbc_queries:get_privacy_list_data(LServer, LUser, Name).
+
+sql_get_privacy_list_data_t(LUser, Name) ->
+    Username = ejabberd_odbc:escape(LUser),
+    SName = ejabberd_odbc:escape(Name),
+    odbc_queries:get_privacy_list_data_t(Username, SName).
+
+sql_get_privacy_list_data_by_id(ID, LServer) ->
+    odbc_queries:get_privacy_list_data_by_id(LServer, ID).
+
+sql_get_privacy_list_data_by_id_t(ID) ->
+    odbc_queries:get_privacy_list_data_by_id_t(ID).
+
+sql_set_default_privacy_list(LUser, Name) ->
+    odbc_queries:set_default_privacy_list(LUser, Name).
+
+sql_unset_default_privacy_list(LUser, LServer) ->
+    odbc_queries:unset_default_privacy_list(LServer, LUser).
+
+sql_remove_privacy_list(LUser, Name) ->
+    odbc_queries:remove_privacy_list(LUser, Name).
+
+sql_add_privacy_list(LUser, Name) ->
+    odbc_queries:add_privacy_list(LUser, Name).
+
+sql_set_privacy_list(ID, RItems) ->
+    odbc_queries:set_privacy_list(ID, RItems).
+
+sql_del_privacy_lists(LUser, LServer) ->
+    odbc_queries:del_privacy_lists(LServer, LUser).
diff --git a/src/mod_private.erl b/src/mod_private.erl
index b4b06450..029789e6 100644
--- a/src/mod_private.erl
+++ b/src/mod_private.erl
@@ -39,12 +39,14 @@
 -include("logger.hrl").
 
 -include("jlib.hrl").
-
--record(private_storage,
-        {usns = {<<"">>, <<"">>, <<"">>} :: {binary(), binary(), binary() |
-                                             '$1' | '_'},
-         xml = #xmlel{} :: xmlel() | '_' | '$1'}).
-
+-include("mod_private.hrl").
+
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #private_storage{}) -> ok | pass.
+-callback set_data(binary(), binary(), [{binary(), xmlel()}]) -> {atomic, any()}.
+-callback get_data(binary(), binary(), binary()) -> {ok, xmlel()} | error.
+-callback get_all_data(binary(), binary()) -> [xmlel()].
+    
 -define(Xmlel_Query(Attrs, Children),
 	#xmlel{name = <<"query">>, attrs = Attrs,
 	       children = Children}).
@@ -52,15 +54,8 @@
 start(Host, Opts) ->
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
                              one_queue),
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(private_storage,
-			      [{disc_only_copies, [node()]},
-			       {attributes,
-				record_info(fields, private_storage)}]),
-	  update_table();
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     ejabberd_hooks:add(remove_user, Host, ?MODULE,
 		       remove_user, 50),
     gen_iq_handler:add_iq_handler(ejabberd_sm, Host,
@@ -139,190 +134,44 @@ filter_xmlels([_ | Xmlels], Data) ->
     filter_xmlels(Xmlels, Data).
 
 set_data(LUser, LServer, Data) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    F = fun () ->
-		lists:foreach(fun (Datum) ->
-				      set_data(LUser, LServer,
-					       Datum, DBType)
-			      end,
-			      Data)
-	end,
-    case DBType of
-	odbc -> ejabberd_odbc:sql_transaction(LServer, F);
-	mnesia -> mnesia:transaction(F);
-	riak -> F()
-    end.
-
-set_data(LUser, LServer, {XmlNS, Xmlel}, mnesia) ->
-    mnesia:write(#private_storage{usns =
-				      {LUser, LServer, XmlNS},
-				  xml = Xmlel});
-set_data(LUser, LServer, {XMLNS, El}, odbc) ->
-    SData = fxml:element_to_binary(El),
-    odbc_queries:set_private_data(LServer, LUser, XMLNS, SData);
-set_data(LUser, LServer, {XMLNS, El}, riak) ->
-    ejabberd_riak:put(#private_storage{usns = {LUser, LServer, XMLNS},
-                                       xml = El},
-		      private_storage_schema(),
-                      [{'2i', [{<<"us">>, {LUser, LServer}}]}]).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:set_data(LUser, LServer, Data).
 
 get_data(LUser, LServer, Data) ->
-    get_data(LUser, LServer,
-	     gen_mod:db_type(LServer, ?MODULE), Data, []).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    get_data(LUser, LServer, Data, Mod, []).
 
-get_data(_LUser, _LServer, _DBType, [],
-	 Storage_Xmlels) ->
+get_data(_LUser, _LServer, [], _Mod, Storage_Xmlels) ->
     lists:reverse(Storage_Xmlels);
-get_data(LUser, LServer, mnesia,
-	 [{XmlNS, Xmlel} | Data], Storage_Xmlels) ->
-    case mnesia:dirty_read(private_storage,
-			   {LUser, LServer, XmlNS})
-	of
-      [#private_storage{xml = Storage_Xmlel}] ->
-	  get_data(LUser, LServer, mnesia, Data,
-		   [Storage_Xmlel | Storage_Xmlels]);
-      _ ->
-	  get_data(LUser, LServer, mnesia, Data,
-		   [Xmlel | Storage_Xmlels])
-    end;
-get_data(LUser, LServer, odbc, [{XMLNS, El} | Els],
-	 Res) ->
-    case catch odbc_queries:get_private_data(LServer,
-					     LUser, XMLNS)
-	of
-      {selected, [{SData}]} ->
-	  case fxml_stream:parse_element(SData) of
-	    Data when is_record(Data, xmlel) ->
-		get_data(LUser, LServer, odbc, Els, [Data | Res])
-	  end;
-      _ -> get_data(LUser, LServer, odbc, Els, [El | Res])
-    end;
-get_data(LUser, LServer, riak, [{XMLNS, El} | Els],
-	 Res) ->
-    case ejabberd_riak:get(private_storage, private_storage_schema(),
-			   {LUser, LServer, XMLNS}) of
-        {ok, #private_storage{xml = NewEl}} ->
-            get_data(LUser, LServer, riak, Els, [NewEl|Res]);
-        _ ->
-            get_data(LUser, LServer, riak, Els, [El|Res])
+get_data(LUser, LServer, [{XmlNS, Xmlel} | Data], Mod, Storage_Xmlels) ->
+    case Mod:get_data(LUser, LServer, XmlNS) of
+	{ok, Storage_Xmlel} ->
+	    get_data(LUser, LServer, Data, Mod, [Storage_Xmlel | Storage_Xmlels]);
+	error ->
+	    get_data(LUser, LServer, Data, Mod, [Xmlel | Storage_Xmlels])
     end.
 
 get_data(LUser, LServer) ->
-    get_all_data(LUser, LServer,
-                 gen_mod:db_type(LServer, ?MODULE)).
-
-get_all_data(LUser, LServer, mnesia) ->
-    lists:flatten(
-      mnesia:dirty_select(private_storage,
-                          [{#private_storage{usns = {LUser, LServer, '_'},
-                                             xml = '$1'},
-                            [], ['$1']}]));
-get_all_data(LUser, LServer, odbc) ->
-    case catch odbc_queries:get_private_data(LServer, LUser) of
-        {selected, Res} ->
-            lists:flatmap(
-              fun({_, SData}) ->
-                      case fxml_stream:parse_element(SData) of
-                          #xmlel{} = El ->
-                              [El];
-                          _ ->
-                              []
-                      end
-              end, Res);
-        _ ->
-            []
-    end;
-get_all_data(LUser, LServer, riak) ->
-    case ejabberd_riak:get_by_index(
-           private_storage, private_storage_schema(),
-	   <<"us">>, {LUser, LServer}) of
-        {ok, Res} ->
-            [El || #private_storage{xml = El} <- Res];
-        _ ->
-            []
-    end.
-
-private_storage_schema() ->
-    {record_info(fields, private_storage), #private_storage{}}.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_all_data(LUser, LServer).
 
 remove_user(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    remove_user(LUser, LServer,
-		gen_mod:db_type(Server, ?MODULE)).
-
-remove_user(LUser, LServer, mnesia) ->
-    F = fun () ->
-		Namespaces = mnesia:select(private_storage,
-					   [{#private_storage{usns =
-								  {LUser,
-								   LServer,
-								   '$1'},
-							      _ = '_'},
-					     [], ['$$']}]),
-		lists:foreach(fun ([Namespace]) ->
-				      mnesia:delete({private_storage,
-						     {LUser, LServer,
-						      Namespace}})
-			      end,
-			      Namespaces)
-	end,
-    mnesia:transaction(F);
-remove_user(LUser, LServer, odbc) ->
-    odbc_queries:del_user_private_storage(LServer, LUser);
-remove_user(LUser, LServer, riak) ->
-    {atomic, ejabberd_riak:delete_by_index(private_storage,
-                                           <<"us">>, {LUser, LServer})}.
+    Mod = gen_mod:db_mod(Server, ?MODULE),
+    Mod:remove_user(LUser, LServer).
 
-update_table() ->
-    Fields = record_info(fields, private_storage),
-    case mnesia:table_info(private_storage, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            private_storage, Fields, set,
-            fun(#private_storage{usns = {U, _, _}}) -> U end,
-            fun(#private_storage{usns = {U, S, NS}, xml = El} = R) ->
-                    R#private_storage{usns = {iolist_to_binary(U),
-                                              iolist_to_binary(S),
-                                              iolist_to_binary(NS)},
-                                      xml = fxml:to_xmlel(El)}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating private_storage table", []),
-	  mnesia:transform_table(private_storage, ignore, Fields)
-    end.
-
-export(_Server) ->
-    [{private_storage,
-      fun(Host, #private_storage{usns = {LUser, LServer, XMLNS},
-                                 xml = Data})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              LXMLNS = ejabberd_odbc:escape(XMLNS),
-              SData =
-                  ejabberd_odbc:escape(fxml:element_to_binary(Data)),
-              odbc_queries:set_private_data_sql(Username, LXMLNS,
-                                                SData);
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select username, namespace, data from private_storage;">>,
-      fun([LUser, XMLNS, XML]) ->
-              El = #xmlel{} = fxml_stream:parse_element(XML),
-              #private_storage{usns = {LUser, LServer, XMLNS},
-                               xml = El}
-      end}].
-
-import(_LServer, mnesia, #private_storage{} = PS) ->
-    mnesia:dirty_write(PS);
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
 
-import(_LServer, riak, #private_storage{usns = {LUser, LServer, _}} = PS) ->
-    ejabberd_riak:put(PS, private_storage_schema(),
-		      [{'2i', [{<<"us">>, {LUser, LServer}}]}]);
-import(_, _, _) ->
-    pass.
+import(LServer, DBType, PD) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, PD).
 
 mod_opt_type(db_type) -> fun gen_mod:v_db/1;
 mod_opt_type(iqdisc) -> fun gen_iq_handler:check_type/1;
diff --git a/src/mod_private_mnesia.erl b/src/mod_private_mnesia.erl
new file mode 100644
index 00000000..7a852c4f
--- /dev/null
+++ b/src/mod_private_mnesia.erl
@@ -0,0 +1,97 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_private_mnesia).
+-behaviour(mod_private).
+
+%% API
+-export([init/2, set_data/3, get_data/3, get_all_data/2, remove_user/2,
+	 import/2]).
+
+-include("jlib.hrl").
+-include("mod_private.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(private_storage,
+			[{disc_only_copies, [node()]},
+			 {attributes,
+			  record_info(fields, private_storage)}]),
+    update_table().
+
+set_data(LUser, LServer, Data) ->
+    F = fun () ->
+		lists:foreach(
+		  fun({XmlNS, Xmlel}) ->
+			  mnesia:write(
+			    #private_storage{
+			       usns = {LUser, LServer, XmlNS},
+			       xml = Xmlel})
+		  end, Data)
+	end,
+    mnesia:transaction(F).
+
+get_data(LUser, LServer, XmlNS) ->
+    case mnesia:dirty_read(private_storage, {LUser, LServer, XmlNS}) of
+	[#private_storage{xml = Storage_Xmlel}] ->
+	    {ok, Storage_Xmlel};
+	_ ->
+	    error
+    end.
+
+get_all_data(LUser, LServer) ->
+    lists:flatten(
+      mnesia:dirty_select(private_storage,
+                          [{#private_storage{usns = {LUser, LServer, '_'},
+                                             xml = '$1'},
+                            [], ['$1']}])).
+
+remove_user(LUser, LServer) ->
+    F = fun () ->
+		Namespaces = mnesia:select(private_storage,
+					   [{#private_storage{usns =
+								  {LUser,
+								   LServer,
+								   '$1'},
+							      _ = '_'},
+					     [], ['$$']}]),
+		lists:foreach(fun ([Namespace]) ->
+				      mnesia:delete({private_storage,
+						     {LUser, LServer,
+						      Namespace}})
+			      end,
+			      Namespaces)
+	end,
+    mnesia:transaction(F).
+
+import(_LServer, #private_storage{} = PS) ->
+    mnesia:dirty_write(PS).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_table() ->
+    Fields = record_info(fields, private_storage),
+    case mnesia:table_info(private_storage, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            private_storage, Fields, set,
+            fun(#private_storage{usns = {U, _, _}}) -> U end,
+            fun(#private_storage{usns = {U, S, NS}, xml = El} = R) ->
+                    R#private_storage{usns = {iolist_to_binary(U),
+                                              iolist_to_binary(S),
+                                              iolist_to_binary(NS)},
+                                      xml = fxml:to_xmlel(El)}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating private_storage table", []),
+	  mnesia:transform_table(private_storage, ignore, Fields)
+    end.
diff --git a/src/mod_private_riak.erl b/src/mod_private_riak.erl
new file mode 100644
index 00000000..11cfa477
--- /dev/null
+++ b/src/mod_private_riak.erl
@@ -0,0 +1,67 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_private_riak).
+
+-behaviour(mod_private).
+
+%% API
+-export([init/2, set_data/3, get_data/3, get_all_data/2, remove_user/2,
+	 import/2]).
+
+-include("jlib.hrl").
+-include("mod_private.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+set_data(LUser, LServer, Data) ->
+    lists:foreach(
+      fun({XMLNS, El}) ->
+	      ejabberd_riak:put(#private_storage{usns = {LUser, LServer, XMLNS},
+						 xml = El},
+				private_storage_schema(),
+				[{'2i', [{<<"us">>, {LUser, LServer}}]}])
+      end, Data),
+    {atomic, ok}.
+
+get_data(LUser, LServer, XMLNS) ->
+    case ejabberd_riak:get(private_storage, private_storage_schema(),
+			   {LUser, LServer, XMLNS}) of
+        {ok, #private_storage{xml = El}} ->
+            {ok, El};
+        _ ->
+	    error
+    end.
+
+get_all_data(LUser, LServer) ->
+    case ejabberd_riak:get_by_index(
+           private_storage, private_storage_schema(),
+	   <<"us">>, {LUser, LServer}) of
+        {ok, Res} ->
+            [El || #private_storage{xml = El} <- Res];
+        _ ->
+            []
+    end.
+
+remove_user(LUser, LServer) ->
+    {atomic, ejabberd_riak:delete_by_index(private_storage,
+                                           <<"us">>, {LUser, LServer})}.
+
+import(_LServer, #private_storage{usns = {LUser, LServer, _}} = PS) ->
+    ejabberd_riak:put(PS, private_storage_schema(),
+		      [{'2i', [{<<"us">>, {LUser, LServer}}]}]).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+private_storage_schema() ->
+    {record_info(fields, private_storage), #private_storage{}}.
diff --git a/src/mod_private_sql.erl b/src/mod_private_sql.erl
new file mode 100644
index 00000000..1b77c48b
--- /dev/null
+++ b/src/mod_private_sql.erl
@@ -0,0 +1,97 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_private_sql).
+
+-behaviour(mod_private).
+
+%% API
+-export([init/2, set_data/3, get_data/3, get_all_data/2, remove_user/2,
+	 import/1, import/2, export/1]).
+
+-include("jlib.hrl").
+-include("mod_private.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+set_data(LUser, LServer, Data) ->
+    F = fun() ->
+		lists:foreach(
+		  fun({XMLNS, El}) ->
+			  SData = fxml:element_to_binary(El),
+			  odbc_queries:set_private_data(
+			    LServer, LUser, XMLNS, SData)
+		  end, Data)
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+get_data(LUser, LServer, XMLNS) ->
+    case catch odbc_queries:get_private_data(LServer, LUser, XMLNS) of
+	{selected, [{SData}]} ->
+	    case fxml_stream:parse_element(SData) of
+		Data when is_record(Data, xmlel) ->
+		    {ok, Data};
+		_ ->
+		    error
+	    end;
+	_ ->
+	    error
+    end.
+
+get_all_data(LUser, LServer) ->
+    case catch odbc_queries:get_private_data(LServer, LUser) of
+        {selected, Res} ->
+            lists:flatmap(
+              fun({_, SData}) ->
+                      case fxml_stream:parse_element(SData) of
+                          #xmlel{} = El ->
+                              [El];
+                          _ ->
+                              []
+                      end
+              end, Res);
+        _ ->
+            []
+    end.
+
+remove_user(LUser, LServer) ->
+    odbc_queries:del_user_private_storage(LServer, LUser).
+
+export(_Server) ->
+    [{private_storage,
+      fun(Host, #private_storage{usns = {LUser, LServer, XMLNS},
+                                 xml = Data})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              LXMLNS = ejabberd_odbc:escape(XMLNS),
+              SData =
+                  ejabberd_odbc:escape(fxml:element_to_binary(Data)),
+              odbc_queries:set_private_data_sql(Username, LXMLNS,
+                                                SData);
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select username, namespace, data from private_storage;">>,
+      fun([LUser, XMLNS, XML]) ->
+              El = #xmlel{} = fxml_stream:parse_element(XML),
+              #private_storage{usns = {LUser, LServer, XMLNS},
+                               xml = El}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
diff --git a/src/mod_roster.erl b/src/mod_roster.erl
index 35072e5f..16354dd8 100644
--- a/src/mod_roster.erl
+++ b/src/mod_roster.erl
@@ -49,7 +49,6 @@
 	 get_jid_info/4, item_to_xml/1, webadmin_page/3,
 	 webadmin_user/4, get_versioning_feature/2,
 	 roster_versioning_enabled/1, roster_version/2,
-	 record_to_string/1, groups_to_string/1,
 	 mod_opt_type/1, set_roster/1]).
 
 -include("ejabberd.hrl").
@@ -65,23 +64,27 @@
 
 -export_type([subscription/0]).
 
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #roster{} | #roster_version{}) -> ok | pass.
+-callback read_roster_version(binary(), binary()) -> binary() | error.
+-callback write_roster_version(binary(), binary(), boolean(), binary()) -> any().
+-callback get_roster(binary(), binary()) -> [#roster{}].
+-callback get_roster_by_jid(binary(), binary(), ljid()) -> #roster{}.
+-callback get_only_items(binary(), binary()) -> [#roster{}].
+-callback roster_subscribe(binary(), binary(), ljid(), #roster{}) -> any().
+-callback transaction(binary(), function()) -> {atomic, any()} | {aborted, any()}.
+-callback get_roster_by_jid_with_groups(binary(), binary(), ljid()) -> #roster{}.
+-callback remove_user(binary(), binary()) -> {atomic, any()}.
+-callback update_roster(binary(), binary(), ljid(), #roster{}) -> any().
+-callback del_roster(binary(), binary(), ljid()) -> any().
+-callback read_subscription_and_groups(binary(), binary(), ljid()) ->
+    {subscription(), [binary()]}.
+
 start(Host, Opts) ->
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
                              one_queue),
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(roster,
-			      [{disc_copies, [node()]},
-			       {attributes, record_info(fields, roster)}]),
-	  mnesia:create_table(roster_version,
-			      [{disc_copies, [node()]},
-			       {attributes,
-				record_info(fields, roster_version)}]),
-	  update_tables(),
-	  mnesia:add_table_index(roster, us),
-	  mnesia:add_table_index(roster_version, us);
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     ejabberd_hooks:add(roster_get, Host, ?MODULE,
 		       get_user_roster, 50),
     ejabberd_hooks:add(roster_in_subscription, Host,
@@ -194,26 +197,8 @@ roster_version(LServer, LUser) ->
     end.
 
 read_roster_version(LUser, LServer) ->
-    read_roster_version(LUser, LServer,
-			gen_mod:db_type(LServer, ?MODULE)).
-
-read_roster_version(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    case mnesia:dirty_read(roster_version, US) of
-      [#roster_version{version = V}] -> V;
-      [] -> error
-    end;
-read_roster_version(LUser, LServer, odbc) ->
-    case odbc_queries:get_roster_version(LServer, LUser) of
-      {selected, [{Version}]} -> Version;
-      {selected, []} -> error
-    end;
-read_roster_version(LServer, LUser, riak) ->
-    case ejabberd_riak:get(roster_version, roster_version_schema(),
-			   {LUser, LServer}) of
-        {ok, #roster_version{version = V}} -> V;
-        _Err -> error
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:read_roster_version(LUser, LServer).
 
 write_roster_version(LUser, LServer) ->
     write_roster_version(LUser, LServer, false).
@@ -223,38 +208,10 @@ write_roster_version_t(LUser, LServer) ->
 
 write_roster_version(LUser, LServer, InTransaction) ->
     Ver = p1_sha:sha(term_to_binary(p1_time_compat:unique_integer())),
-    write_roster_version(LUser, LServer, InTransaction, Ver,
-			 gen_mod:db_type(LServer, ?MODULE)),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:write_roster_version(LUser, LServer, InTransaction, Ver),
     Ver.
 
-write_roster_version(LUser, LServer, InTransaction, Ver,
-		     mnesia) ->
-    US = {LUser, LServer},
-    if InTransaction ->
-	   mnesia:write(#roster_version{us = US, version = Ver});
-       true ->
-	   mnesia:dirty_write(#roster_version{us = US,
-					      version = Ver})
-    end;
-write_roster_version(LUser, LServer, InTransaction, Ver,
-		     odbc) ->
-    Username = ejabberd_odbc:escape(LUser),
-    EVer = ejabberd_odbc:escape(Ver),
-    if InTransaction ->
-	   odbc_queries:set_roster_version(Username, EVer);
-       true ->
-	   odbc_queries:sql_transaction(LServer,
-					fun () ->
-						odbc_queries:set_roster_version(Username,
-										EVer)
-					end)
-    end;
-write_roster_version(LUser, LServer, _InTransaction, Ver,
-		     riak) ->
-    US = {LUser, LServer},
-    ejabberd_riak:put(#roster_version{us = US, version = Ver},
-		      roster_version_schema()).
-
 %% Load roster from DB only if neccesary.
 %% It is neccesary if
 %%     - roster versioning is disabled in server OR
@@ -350,56 +307,8 @@ get_user_roster(Acc, {LUser, LServer}) ->
       ++ Acc.
 
 get_roster(LUser, LServer) ->
-    get_roster(LUser, LServer,
-	       gen_mod:db_type(LServer, ?MODULE)).
-
-get_roster(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    case catch mnesia:dirty_index_read(roster, US,
-				       #roster.us)
-	of
-      Items  when is_list(Items)-> Items;
-      _ -> []
-    end;
-get_roster(LUser, LServer, riak) ->
-    case ejabberd_riak:get_by_index(roster, roster_schema(),
-				    <<"us">>, {LUser, LServer}) of
-        {ok, Items} -> Items;
-        _Err -> []
-    end;
-get_roster(LUser, LServer, odbc) ->
-    case catch odbc_queries:get_roster(LServer, LUser) of
-        {selected, Items} when is_list(Items) ->
-            JIDGroups = case catch odbc_queries:get_roster_jid_groups(
-                                     LServer, LUser) of
-                            {selected, JGrps}
-                            when is_list(JGrps) ->
-                                JGrps;
-                            _ -> []
-                        end,
-            GroupsDict = lists:foldl(fun({J, G}, Acc) ->
-                                             dict:append(J, G, Acc)
-                                     end,
-                                     dict:new(), JIDGroups),
-            RItems =
-                lists:flatmap(
-                  fun(I) ->
-                          case raw_to_record(LServer, I) of
-                              %% Bad JID in database:
-                              error -> [];
-                              R ->
-                                  SJID = jid:to_string(R#roster.jid),
-                                  Groups = case dict:find(SJID, GroupsDict) of
-                                               {ok, Gs} -> Gs;
-                                               error -> []
-                                           end,
-                                  [R#roster{groups = Groups}]
-                          end
-                  end,
-                  Items),
-            RItems;
-        _ -> []
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_roster(LUser, LServer).
 
 set_roster(#roster{us = {LUser, LServer}, jid = LJID} = Item) ->
     transaction(
@@ -437,48 +346,8 @@ item_to_xml(Item) ->
 	   children = SubEls}.
 
 get_roster_by_jid_t(LUser, LServer, LJID) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    get_roster_by_jid_t(LUser, LServer, LJID, DBType).
-
-get_roster_by_jid_t(LUser, LServer, LJID, mnesia) ->
-    case mnesia:read({roster, {LUser, LServer, LJID}}) of
-      [] ->
-	  #roster{usj = {LUser, LServer, LJID},
-		  us = {LUser, LServer}, jid = LJID};
-      [I] ->
-	  I#roster{jid = LJID, name = <<"">>, groups = [],
-		   xs = []}
-    end;
-get_roster_by_jid_t(LUser, LServer, LJID, odbc) ->
-    {selected, Res} =
-	odbc_queries:get_roster_by_jid(LServer, LUser, jid:to_string(LJID)),
-    case Res of
-      [] ->
-	  #roster{usj = {LUser, LServer, LJID},
-		  us = {LUser, LServer}, jid = LJID};
-      [I] ->
-	  R = raw_to_record(LServer, I),
-	  case R of
-	    %% Bad JID in database:
-	    error ->
-		#roster{usj = {LUser, LServer, LJID},
-			us = {LUser, LServer}, jid = LJID};
-	    _ ->
-		R#roster{usj = {LUser, LServer, LJID},
-			 us = {LUser, LServer}, jid = LJID, name = <<"">>}
-	  end
-    end;
-get_roster_by_jid_t(LUser, LServer, LJID, riak) ->
-    case ejabberd_riak:get(roster, roster_schema(), {LUser, LServer, LJID}) of
-        {ok, I} ->
-            I#roster{jid = LJID, name = <<"">>, groups = [],
-                     xs = []};
-        {error, notfound} ->
-            #roster{usj = {LUser, LServer, LJID},
-                    us = {LUser, LServer}, jid = LJID};
-        Err ->
-            exit(Err)
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_roster_by_jid(LUser, LServer, LJID).
 
 try_process_iq_set(From, To, #iq{sub_el = SubEl, lang = Lang} = IQ) ->
     #jid{server = Server} = From,
@@ -632,77 +501,37 @@ push_item_version(Server, User, From, Item,
 		  end,
 		  ejabberd_sm:get_user_resources(User, Server)).
 
-get_subscription_lists(Acc, User, Server) ->
+get_subscription_lists(_Acc, User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    Items = get_subscription_lists(Acc, LUser, LServer,
-				   DBType),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Items = Mod:get_only_items(LUser, LServer),
     fill_subscription_lists(LServer, Items, [], []).
 
-get_subscription_lists(_, LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    case mnesia:dirty_index_read(roster, US, #roster.us) of
-      Items when is_list(Items) -> Items;
-      _ -> []
-    end;
-get_subscription_lists(_, LUser, LServer, odbc) ->
-    case catch odbc_queries:get_roster(LServer, LUser) of
-        {selected, Items} when is_list(Items) ->
-            lists:map(fun(I) -> raw_to_record(LServer, I) end, Items);
-      _ -> []
-    end;
-get_subscription_lists(_, LUser, LServer, riak) ->
-    case ejabberd_riak:get_by_index(roster, roster_schema(),
-				    <<"us">>, {LUser, LServer}) of
-        {ok, Items} -> Items;
-        _Err -> []
-    end.
-
-fill_subscription_lists(LServer, [#roster{} = I | Is],
-			F, T) ->
+fill_subscription_lists(LServer, [I | Is], F, T) ->
     J = element(3, I#roster.usj),
     case I#roster.subscription of
-      both ->
-	  fill_subscription_lists(LServer, Is, [J | F], [J | T]);
-      from ->
-	  fill_subscription_lists(LServer, Is, [J | F], T);
-      to -> fill_subscription_lists(LServer, Is, F, [J | T]);
-      _ -> fill_subscription_lists(LServer, Is, F, T)
-    end;
-fill_subscription_lists(LServer, [RawI | Is], F, T) ->
-    I = raw_to_record(LServer, RawI),
-    case I of
-      %% Bad JID in database:
-      error -> fill_subscription_lists(LServer, Is, F, T);
-      _ -> fill_subscription_lists(LServer, [I | Is], F, T)
+	both ->
+	    fill_subscription_lists(LServer, Is, [J | F], [J | T]);
+	from ->
+	    fill_subscription_lists(LServer, Is, [J | F], T);
+	to -> fill_subscription_lists(LServer, Is, F, [J | T]);
+	_ -> fill_subscription_lists(LServer, Is, F, T)
     end;
-fill_subscription_lists(_LServer, [], F, T) -> {F, T}.
+fill_subscription_lists(_LServer, [], F, T) ->
+    {F, T}.
 
 ask_to_pending(subscribe) -> out;
 ask_to_pending(unsubscribe) -> none;
 ask_to_pending(Ask) -> Ask.
 
 roster_subscribe_t(LUser, LServer, LJID, Item) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    roster_subscribe_t(LUser, LServer, LJID, Item, DBType).
-
-roster_subscribe_t(_LUser, _LServer, _LJID, Item,
-		   mnesia) ->
-    mnesia:write(Item);
-roster_subscribe_t(_LUser, _LServer, _LJID, Item, odbc) ->
-    ItemVals = record_to_row(Item),
-    odbc_queries:roster_subscribe(ItemVals);
-roster_subscribe_t(LUser, LServer, _LJID, Item, riak) ->
-    ejabberd_riak:put(Item, roster_schema(),
-                      [{'2i', [{<<"us">>, {LUser, LServer}}]}]).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:roster_subscribe(LUser, LServer, LJID, Item).
 
 transaction(LServer, F) ->
-    case gen_mod:db_type(LServer, ?MODULE) of
-      mnesia -> mnesia:transaction(F);
-      odbc -> ejabberd_odbc:sql_transaction(LServer, F);
-      riak -> {atomic, F()}
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:transaction(LServer, F).
 
 in_subscription(_, User, Server, JID, Type, Reason) ->
     process_subscription(in, User, Server, JID, Type,
@@ -712,45 +541,8 @@ out_subscription(User, Server, JID, Type) ->
     process_subscription(out, User, Server, JID, Type, <<"">>).
 
 get_roster_by_jid_with_groups_t(LUser, LServer, LJID) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    get_roster_by_jid_with_groups_t(LUser, LServer, LJID,
-				    DBType).
-
-get_roster_by_jid_with_groups_t(LUser, LServer, LJID,
-				mnesia) ->
-    case mnesia:read({roster, {LUser, LServer, LJID}}) of
-      [] ->
-	  #roster{usj = {LUser, LServer, LJID},
-		  us = {LUser, LServer}, jid = LJID};
-      [I] -> I
-    end;
-get_roster_by_jid_with_groups_t(LUser, LServer, LJID,
-				odbc) ->
-    SJID = jid:to_string(LJID),
-    case odbc_queries:get_roster_by_jid(LServer, LUser, SJID) of
-      {selected, [I]} ->
-            R = raw_to_record(LServer, I),
-            Groups =
-                case odbc_queries:get_roster_groups(LServer, LUser, SJID) of
-                    {selected, JGrps} when is_list(JGrps) ->
-                        [JGrp || {JGrp} <- JGrps];
-                    _ -> []
-                end,
-            R#roster{groups = Groups};
-      {selected, []} ->
-	  #roster{usj = {LUser, LServer, LJID},
-		  us = {LUser, LServer}, jid = LJID}
-    end;
-get_roster_by_jid_with_groups_t(LUser, LServer, LJID, riak) ->
-    case ejabberd_riak:get(roster, roster_schema(), {LUser, LServer, LJID}) of
-        {ok, I} ->
-            I;
-        {error, notfound} ->
-            #roster{usj = {LUser, LServer, LJID},
-                    us = {LUser, LServer}, jid = LJID};
-        Err ->
-            exit(Err)
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_roster_by_jid_with_groups(LUser, LServer, LJID).
 
 process_subscription(Direction, User, Server, JID1,
 		     Type, Reason) ->
@@ -948,21 +740,8 @@ remove_user(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
     send_unsubscription_to_rosteritems(LUser, LServer),
-    remove_user(LUser, LServer,
-		gen_mod:db_type(LServer, ?MODULE)).
-
-remove_user(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () ->
-		lists:foreach(fun (R) -> mnesia:delete_object(R) end,
-			      mnesia:index_read(roster, US, #roster.us))
-	end,
-    mnesia:transaction(F);
-remove_user(LUser, LServer, odbc) ->
-    odbc_queries:del_user_roster_t(LServer, LUser),
-    ok;
-remove_user(LUser, LServer, riak) ->
-    {atomic, ejabberd_riak:delete_by_index(roster, <<"us">>, {LUser, LServer})}.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_user(LUser, LServer).
 
 %% For each contact with Subscription:
 %% Both or From, send a "unsubscribed" presence stanza;
@@ -1020,33 +799,12 @@ set_items(User, Server, SubEl) ->
     transaction(LServer, F).
 
 update_roster_t(LUser, LServer, LJID, Item) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    update_roster_t(LUser, LServer, LJID, Item, DBType).
-
-update_roster_t(_LUser, _LServer, _LJID, Item,
-		mnesia) ->
-    mnesia:write(Item);
-update_roster_t(LUser, LServer, LJID, Item, odbc) ->
-    SJID = jid:to_string(LJID),
-    ItemVals = record_to_row(Item),
-    ItemGroups = Item#roster.groups,
-    odbc_queries:update_roster(LServer, LUser, SJID, ItemVals,
-                               ItemGroups);
-update_roster_t(LUser, LServer, _LJID, Item, riak) ->
-    ejabberd_riak:put(Item, roster_schema(),
-                      [{'2i', [{<<"us">>, {LUser, LServer}}]}]).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:update_roster(LUser, LServer, LJID, Item).
 
 del_roster_t(LUser, LServer, LJID) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    del_roster_t(LUser, LServer, LJID, DBType).
-
-del_roster_t(LUser, LServer, LJID, mnesia) ->
-    mnesia:delete({roster, {LUser, LServer, LJID}});
-del_roster_t(LUser, LServer, LJID, odbc) ->
-    SJID = jid:to_string(LJID),
-    odbc_queries:del_roster(LServer, LUser, SJID);
-del_roster_t(LUser, LServer, LJID, riak) ->
-    ejabberd_riak:delete(roster, {LUser, LServer, LJID}).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:del_roster(LUser, LServer, LJID).
 
 process_item_set_t(LUser, LServer,
 		   #xmlel{attrs = Attrs, children = Els}) ->
@@ -1109,13 +867,12 @@ process_item_attrs_ws(Item, []) -> Item.
 
 get_in_pending_subscriptions(Ls, User, Server) ->
     LServer = jid:nameprep(Server),
-    get_in_pending_subscriptions(Ls, User, Server,
-				 gen_mod:db_type(LServer, ?MODULE)).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    get_in_pending_subscriptions(Ls, User, Server, Mod).
 
-get_in_pending_subscriptions(Ls, User, Server, DBType)
-  when DBType == mnesia; DBType == riak ->
+get_in_pending_subscriptions(Ls, User, Server, Mod) ->
     JID = jid:make(User, Server, <<"">>),
-    Result = get_roster(JID#jid.luser, JID#jid.lserver, DBType),
+    Result = Mod:get_only_items(JID#jid.luser, JID#jid.lserver),
     Ls ++ lists:map(fun (R) ->
                             Message = R#roster.askmessage,
                             Status = if is_binary(Message) -> (Message);
@@ -1140,93 +897,15 @@ get_in_pending_subscriptions(Ls, User, Server, DBType)
                                              _ -> false
                                          end
                                  end,
-                                 Result));
-get_in_pending_subscriptions(Ls, User, Server, odbc) ->
-    JID = jid:make(User, Server, <<"">>),
-    LUser = JID#jid.luser,
-    LServer = JID#jid.lserver,
-    case catch odbc_queries:get_roster(LServer, LUser) of
-        {selected, Items} when is_list(Items) ->
-	  Ls ++
-	    lists:map(fun (R) ->
-			      Message = R#roster.askmessage,
-			      #xmlel{name = <<"presence">>,
-				     attrs =
-					 [{<<"from">>,
-					   jid:to_string(R#roster.jid)},
-					  {<<"to">>, jid:to_string(JID)},
-					  {<<"type">>, <<"subscribe">>}],
-				     children =
-					 [#xmlel{name = <<"status">>,
-						 attrs = [],
-						 children =
-						     [{xmlcdata, Message}]}]}
-		      end,
-		      lists:flatmap(fun (I) ->
-					    case raw_to_record(LServer, I) of
-					      %% Bad JID in database:
-					      error -> [];
-					      R ->
-						  case R#roster.ask of
-						    in -> [R];
-						    both -> [R];
-						    _ -> []
-						  end
-					    end
-				    end,
-				    Items));
-      _ -> Ls
-    end.
+                                 Result)).
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 read_subscription_and_groups(User, Server, LJID) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    read_subscription_and_groups(LUser, LServer, LJID,
-				 gen_mod:db_type(LServer, ?MODULE)).
-
-read_subscription_and_groups(LUser, LServer, LJID,
-			     mnesia) ->
-    case catch mnesia:dirty_read(roster,
-				 {LUser, LServer, LJID})
-	of
-      [#roster{subscription = Subscription,
-	       groups = Groups}] ->
-	  {Subscription, Groups};
-      _ -> error
-    end;
-read_subscription_and_groups(LUser, LServer, LJID,
-			     odbc) ->
-    SJID = jid:to_string(LJID),
-    case catch odbc_queries:get_subscription(LServer, LUser, SJID) of
-      {selected, [{SSubscription}]} ->
-	  Subscription = case SSubscription of
-			   <<"B">> -> both;
-			   <<"T">> -> to;
-			   <<"F">> -> from;
-			   _ -> none
-			 end,
-	  Groups = case catch
-			  odbc_queries:get_rostergroup_by_jid(LServer, LUser,
-							      SJID)
-		       of
-		     {selected, JGrps} when is_list(JGrps) ->
-			 [JGrp || {JGrp} <- JGrps];
-		     _ -> []
-		   end,
-	  {Subscription, Groups};
-      _ -> error
-    end;
-read_subscription_and_groups(LUser, LServer, LJID,
-			     riak) ->
-    case ejabberd_riak:get(roster, roster_schema(), {LUser, LServer, LJID}) of
-        {ok, #roster{subscription = Subscription,
-                     groups = Groups}} ->
-            {Subscription, Groups};
-        _ ->
-            error
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:read_subscription_and_groups(LUser, LServer, LJID).
 
 get_jid_info(_, User, Server, JID) ->
     LJID = jid:tolower(JID),
@@ -1246,155 +925,6 @@ get_jid_info(_, User, Server, JID) ->
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-raw_to_record(LServer,
-	      [User, SJID, Nick, SSubscription, SAsk, SAskMessage,
-	       _SServer, _SSubscribe, _SType]) ->
-    raw_to_record(LServer,
-                  {User, SJID, Nick, SSubscription, SAsk, SAskMessage,
-                   _SServer, _SSubscribe, _SType});
-raw_to_record(LServer,
-	      {User, SJID, Nick, SSubscription, SAsk, SAskMessage,
-	       _SServer, _SSubscribe, _SType}) ->
-    case jid:from_string(SJID) of
-      error -> error;
-      JID ->
-	  LJID = jid:tolower(JID),
-	  Subscription = case SSubscription of
-			   <<"B">> -> both;
-			   <<"T">> -> to;
-			   <<"F">> -> from;
-			   _ -> none
-			 end,
-	  Ask = case SAsk of
-		  <<"S">> -> subscribe;
-		  <<"U">> -> unsubscribe;
-		  <<"B">> -> both;
-		  <<"O">> -> out;
-		  <<"I">> -> in;
-		  _ -> none
-		end,
-	  #roster{usj = {User, LServer, LJID},
-		  us = {User, LServer}, jid = LJID, name = Nick,
-		  subscription = Subscription, ask = Ask,
-		  askmessage = SAskMessage}
-    end.
-
-record_to_string(#roster{us = {User, _Server},
-			 jid = JID, name = Name, subscription = Subscription,
-			 ask = Ask, askmessage = AskMessage}) ->
-    Username = ejabberd_odbc:escape(User),
-    SJID =
-	ejabberd_odbc:escape(jid:to_string(jid:tolower(JID))),
-    Nick = ejabberd_odbc:escape(Name),
-    SSubscription = case Subscription of
-		      both -> <<"B">>;
-		      to -> <<"T">>;
-		      from -> <<"F">>;
-		      none -> <<"N">>
-		    end,
-    SAsk = case Ask of
-	     subscribe -> <<"S">>;
-	     unsubscribe -> <<"U">>;
-	     both -> <<"B">>;
-	     out -> <<"O">>;
-	     in -> <<"I">>;
-	     none -> <<"N">>
-	   end,
-    SAskMessage = ejabberd_odbc:escape(AskMessage),
-    [Username, SJID, Nick, SSubscription, SAsk, SAskMessage,
-     <<"N">>, <<"">>, <<"item">>].
-
-record_to_row(
-  #roster{us = {LUser, _LServer},
-          jid = JID, name = Name, subscription = Subscription,
-          ask = Ask, askmessage = AskMessage}) ->
-    SJID = jid:to_string(jid:tolower(JID)),
-    SSubscription = case Subscription of
-		      both -> <<"B">>;
-		      to -> <<"T">>;
-		      from -> <<"F">>;
-		      none -> <<"N">>
-		    end,
-    SAsk = case Ask of
-	     subscribe -> <<"S">>;
-	     unsubscribe -> <<"U">>;
-	     both -> <<"B">>;
-	     out -> <<"O">>;
-	     in -> <<"I">>;
-	     none -> <<"N">>
-	   end,
-    {LUser, SJID, Name, SSubscription, SAsk, AskMessage}.
-
-groups_to_string(#roster{us = {User, _Server},
-			 jid = JID, groups = Groups}) ->
-    Username = ejabberd_odbc:escape(User),
-    SJID =
-	ejabberd_odbc:escape(jid:to_string(jid:tolower(JID))),
-    lists:foldl(fun (<<"">>, Acc) -> Acc;
-		    (Group, Acc) ->
-			G = ejabberd_odbc:escape(Group),
-			[[Username, SJID, G] | Acc]
-		end,
-		[], Groups).
-
-update_tables() ->
-    update_roster_table(),
-    update_roster_version_table().
-
-update_roster_table() ->
-    Fields = record_info(fields, roster),
-    case mnesia:table_info(roster, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            roster, Fields, set,
-            fun(#roster{usj = {U, _, _}}) -> U end,
-            fun(#roster{usj = {U, S, {LU, LS, LR}},
-                        us = {U1, S1},
-                        jid = {U2, S2, R2},
-                        name = Name,
-                        groups = Gs,
-                        askmessage = Ask,
-                        xs = Xs} = R) ->
-                    R#roster{usj = {iolist_to_binary(U),
-                                    iolist_to_binary(S),
-                                    {iolist_to_binary(LU),
-                                     iolist_to_binary(LS),
-                                     iolist_to_binary(LR)}},
-                             us = {iolist_to_binary(U1),
-                                   iolist_to_binary(S1)},
-                             jid = {iolist_to_binary(U2),
-                                    iolist_to_binary(S2),
-                                    iolist_to_binary(R2)},
-                             name = iolist_to_binary(Name),
-                             groups = [iolist_to_binary(G) || G <- Gs],
-                             askmessage = try iolist_to_binary(Ask)
-					  catch _:_ -> <<"">> end,
-                             xs = [fxml:to_xmlel(X) || X <- Xs]}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating roster table", []),
-	  mnesia:transform_table(roster, ignore, Fields)
-    end.
-
-%% Convert roster table to support virtual host
-%% Convert roster table: xattrs fields become
-update_roster_version_table() ->
-    Fields = record_info(fields, roster_version),
-    case mnesia:table_info(roster_version, attributes) of
-        Fields ->
-            ejabberd_config:convert_table_to_binary(
-              roster_version, Fields, set,
-              fun(#roster_version{us = {U, _}}) -> U end,
-              fun(#roster_version{us = {U, S}, version = Ver} = R) ->
-                      R#roster_version{us = {iolist_to_binary(U),
-                                             iolist_to_binary(S)},
-                                       version = iolist_to_binary(Ver)}
-              end);
-        _ ->
-            ?INFO_MSG("Recreating roster_version table", []),
-            mnesia:transform_table(roster_version, ignore, Fields)
-    end.
-
 webadmin_page(_, Host,
 	      #request{us = _US, path = [<<"user">>, U, <<"roster">>],
 		       q = Query, lang = Lang} =
@@ -1692,68 +1222,17 @@ is_managed_from_id(<<"roster-remotely-managed">>) ->
 is_managed_from_id(_Id) ->
     false.
 
-roster_schema() ->
-    {record_info(fields, roster), #roster{}}.
-
-roster_version_schema() ->
-    {record_info(fields, roster_version), #roster_version{}}.
-
-export(_Server) ->
-    [{roster,
-      fun(Host, #roster{usj = {LUser, LServer, LJID}} = R)
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              SJID = ejabberd_odbc:escape(jid:to_string(LJID)),
-              ItemVals = record_to_string(R),
-              ItemGroups = groups_to_string(R),
-              odbc_queries:update_roster_sql(Username, SJID,
-                                             ItemVals, ItemGroups);
-        (_Host, _R) ->
-              []
-      end},
-     {roster_version,
-      fun(Host, #roster_version{us = {LUser, LServer}, version = Ver})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              SVer = ejabberd_odbc:escape(Ver),
-              [[<<"delete from roster_version where username='">>,
-                Username, <<"';">>],
-               [<<"insert into roster_version(username, version) values('">>,
-                Username, <<"', '">>, SVer, <<"');">>]];
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select username, jid, nick, subscription, "
-        "ask, askmessage, server, subscribe, type from rosterusers;">>,
-      fun([LUser, JID|_] = Row) ->
-              Item = raw_to_record(LServer, Row),
-              Username = ejabberd_odbc:escape(LUser),
-              SJID = ejabberd_odbc:escape(JID),
-              {selected, _, Rows} =
-                  ejabberd_odbc:sql_query_t(
-                    [<<"select grp from rostergroups where username='">>,
-                     Username, <<"' and jid='">>, SJID, <<"'">>]),
-              Groups = [Grp || [Grp] <- Rows],
-              Item#roster{groups = Groups}
-      end},
-     {<<"select username, version from roster_version;">>,
-      fun([LUser, Ver]) ->
-              #roster_version{us = {LUser, LServer}, version = Ver}
-      end}].
-
-import(_LServer, mnesia, #roster{} = R) ->
-    mnesia:dirty_write(R);
-import(_LServer, mnesia, #roster_version{} = RV) ->
-    mnesia:dirty_write(RV);
-import(_LServer, riak, #roster{us = {LUser, LServer}} = R) ->
-    ejabberd_riak:put(R, roster_schema(),
-		      [{'2i', [{<<"us">>, {LUser, LServer}}]}]);
-import(_LServer, riak, #roster_version{} = RV) ->
-    ejabberd_riak:put(RV, roster_version_schema());
-import(_, _, _) ->
-    pass.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
+
+import(LServer, DBType, R) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, R).
 
 mod_opt_type(access) ->
     fun (A) when is_atom(A) -> A end;
diff --git a/src/mod_roster_mnesia.erl b/src/mod_roster_mnesia.erl
new file mode 100644
index 00000000..ddfa34d6
--- /dev/null
+++ b/src/mod_roster_mnesia.erl
@@ -0,0 +1,171 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_roster_mnesia).
+
+-behaviour(mod_roster).
+
+%% API
+-export([init/2, read_roster_version/2, write_roster_version/4,
+	 get_roster/2, get_roster_by_jid/3, get_only_items/2,
+	 roster_subscribe/4, get_roster_by_jid_with_groups/3,
+	 remove_user/2, update_roster/4, del_roster/3, transaction/2,
+	 read_subscription_and_groups/3, import/2]).
+
+-include("jlib.hrl").
+-include("mod_roster.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(roster,
+			[{disc_copies, [node()]},
+			 {attributes, record_info(fields, roster)}]),
+    mnesia:create_table(roster_version,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, roster_version)}]),
+    update_tables(),
+    mnesia:add_table_index(roster, us),
+    mnesia:add_table_index(roster_version, us).
+
+read_roster_version(LUser, LServer) ->
+    US = {LUser, LServer},
+    case mnesia:dirty_read(roster_version, US) of
+	[#roster_version{version = V}] -> V;
+	[] -> error
+    end.
+
+write_roster_version(LUser, LServer, InTransaction, Ver) ->
+    US = {LUser, LServer},
+    if InTransaction ->
+	    mnesia:write(#roster_version{us = US, version = Ver});
+       true ->
+	    mnesia:dirty_write(#roster_version{us = US, version = Ver})
+    end.
+
+get_roster(LUser, LServer) ->
+    mnesia:dirty_index_read(roster, {LUser, LServer}, #roster.us).
+
+get_roster_by_jid(LUser, LServer, LJID) ->
+    case mnesia:read({roster, {LUser, LServer, LJID}}) of
+	[] ->
+	    #roster{usj = {LUser, LServer, LJID},
+		    us = {LUser, LServer}, jid = LJID};
+	[I] ->
+	    I#roster{jid = LJID, name = <<"">>, groups = [],
+		     xs = []}
+    end.
+
+get_only_items(LUser, LServer) ->
+    get_roster(LUser, LServer).
+
+roster_subscribe(_LUser, _LServer, _LJID, Item) ->
+    mnesia:write(Item).
+
+get_roster_by_jid_with_groups(LUser, LServer, LJID) ->
+    case mnesia:read({roster, {LUser, LServer, LJID}}) of
+	[] ->
+	    #roster{usj = {LUser, LServer, LJID},
+		    us = {LUser, LServer}, jid = LJID};
+	[I] -> I
+    end.
+
+remove_user(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		lists:foreach(
+		  fun (R) -> mnesia:delete_object(R) end,
+		  mnesia:index_read(roster, US, #roster.us))
+	end,
+    mnesia:transaction(F).
+
+update_roster(_LUser, _LServer, _LJID, Item) ->
+    mnesia:write(Item).
+
+del_roster(LUser, LServer, LJID) ->
+    mnesia:delete({roster, {LUser, LServer, LJID}}).
+
+read_subscription_and_groups(LUser, LServer, LJID) ->
+    case mnesia:dirty_read(roster, {LUser, LServer, LJID}) of
+	[#roster{subscription = Subscription, groups = Groups}] ->
+	    {Subscription, Groups};
+	_ ->
+	    error
+    end.
+
+transaction(_LServer, F) ->
+    mnesia:transaction(F).
+
+import(_LServer, #roster{} = R) ->
+    mnesia:dirty_write(R);
+import(_LServer, #roster_version{} = RV) ->
+    mnesia:dirty_write(RV).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_tables() ->
+    update_roster_table(),
+    update_roster_version_table().
+
+update_roster_table() ->
+    Fields = record_info(fields, roster),
+    case mnesia:table_info(roster, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            roster, Fields, set,
+            fun(#roster{usj = {U, _, _}}) -> U end,
+            fun(#roster{usj = {U, S, {LU, LS, LR}},
+                        us = {U1, S1},
+                        jid = {U2, S2, R2},
+                        name = Name,
+                        groups = Gs,
+                        askmessage = Ask,
+                        xs = Xs} = R) ->
+                    R#roster{usj = {iolist_to_binary(U),
+                                    iolist_to_binary(S),
+                                    {iolist_to_binary(LU),
+                                     iolist_to_binary(LS),
+                                     iolist_to_binary(LR)}},
+                             us = {iolist_to_binary(U1),
+                                   iolist_to_binary(S1)},
+                             jid = {iolist_to_binary(U2),
+                                    iolist_to_binary(S2),
+                                    iolist_to_binary(R2)},
+                             name = iolist_to_binary(Name),
+                             groups = [iolist_to_binary(G) || G <- Gs],
+                             askmessage = try iolist_to_binary(Ask)
+					  catch _:_ -> <<"">> end,
+                             xs = [fxml:to_xmlel(X) || X <- Xs]}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating roster table", []),
+	  mnesia:transform_table(roster, ignore, Fields)
+    end.
+
+%% Convert roster table to support virtual host
+%% Convert roster table: xattrs fields become
+update_roster_version_table() ->
+    Fields = record_info(fields, roster_version),
+    case mnesia:table_info(roster_version, attributes) of
+        Fields ->
+            ejabberd_config:convert_table_to_binary(
+              roster_version, Fields, set,
+              fun(#roster_version{us = {U, _}}) -> U end,
+              fun(#roster_version{us = {U, S}, version = Ver} = R) ->
+                      R#roster_version{us = {iolist_to_binary(U),
+                                             iolist_to_binary(S)},
+                                       version = iolist_to_binary(Ver)}
+              end);
+        _ ->
+            ?INFO_MSG("Recreating roster_version table", []),
+            mnesia:transform_table(roster_version, ignore, Fields)
+    end.
diff --git a/src/mod_roster_riak.erl b/src/mod_roster_riak.erl
new file mode 100644
index 00000000..38e87382
--- /dev/null
+++ b/src/mod_roster_riak.erl
@@ -0,0 +1,113 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_roster_riak).
+
+
+-behaviour(mod_roster).
+
+%% API
+-export([init/2, read_roster_version/2, write_roster_version/4,
+	 get_roster/2, get_roster_by_jid/3,
+	 roster_subscribe/4, get_roster_by_jid_with_groups/3,
+	 remove_user/2, update_roster/4, del_roster/3, transaction/2,
+	 read_subscription_and_groups/3, get_only_items/2, import/2]).
+
+-include("jlib.hrl").
+-include("mod_roster.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+read_roster_version(LUser, LServer) ->
+    case ejabberd_riak:get(roster_version, roster_version_schema(),
+			   {LUser, LServer}) of
+        {ok, #roster_version{version = V}} -> V;
+        _Err -> error
+    end.
+
+write_roster_version(LUser, LServer, _InTransaction, Ver) ->
+    US = {LUser, LServer},
+    ejabberd_riak:put(#roster_version{us = US, version = Ver},
+		      roster_version_schema()).
+
+get_roster(LUser, LServer) ->
+    case ejabberd_riak:get_by_index(roster, roster_schema(),
+				    <<"us">>, {LUser, LServer}) of
+        {ok, Items} -> Items;
+        _Err -> []
+    end.
+
+get_roster_by_jid(LUser, LServer, LJID) ->
+    case ejabberd_riak:get(roster, roster_schema(), {LUser, LServer, LJID}) of
+        {ok, I} ->
+            I#roster{jid = LJID, name = <<"">>, groups = [], xs = []};
+        {error, notfound} ->
+            #roster{usj = {LUser, LServer, LJID},
+                    us = {LUser, LServer}, jid = LJID};
+        Err ->
+            exit(Err)
+    end.
+
+get_only_items(LUser, LServer) ->
+    get_roster(LUser, LServer).
+
+roster_subscribe(LUser, LServer, _LJID, Item) ->
+    ejabberd_riak:put(Item, roster_schema(),
+                      [{'2i', [{<<"us">>, {LUser, LServer}}]}]).
+
+transaction(_LServer, F) ->
+    {atomic, F()}.
+
+get_roster_by_jid_with_groups(LUser, LServer, LJID) ->
+    case ejabberd_riak:get(roster, roster_schema(), {LUser, LServer, LJID}) of
+        {ok, I} ->
+            I;
+        {error, notfound} ->
+            #roster{usj = {LUser, LServer, LJID},
+                    us = {LUser, LServer}, jid = LJID};
+        Err ->
+            exit(Err)
+    end.
+
+remove_user(LUser, LServer) ->
+    {atomic, ejabberd_riak:delete_by_index(roster, <<"us">>, {LUser, LServer})}.
+
+update_roster(LUser, LServer, _LJID, Item) ->
+    ejabberd_riak:put(Item, roster_schema(),
+                      [{'2i', [{<<"us">>, {LUser, LServer}}]}]).
+
+del_roster(LUser, LServer, LJID) ->
+    ejabberd_riak:delete(roster, {LUser, LServer, LJID}).
+
+read_subscription_and_groups(LUser, LServer, LJID) ->
+    case ejabberd_riak:get(roster, roster_schema(), {LUser, LServer, LJID}) of
+        {ok, #roster{subscription = Subscription,
+                     groups = Groups}} ->
+            {Subscription, Groups};
+        _ ->
+            error
+    end.
+
+import(_LServer, #roster{us = {LUser, LServer}} = R) ->
+    ejabberd_riak:put(R, roster_schema(),
+		      [{'2i', [{<<"us">>, {LUser, LServer}}]}]);
+import(_LServer, #roster_version{} = RV) ->
+    ejabberd_riak:put(RV, roster_version_schema()).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+roster_schema() ->
+    {record_info(fields, roster), #roster{}}.
+
+roster_version_schema() ->
+    {record_info(fields, roster_version), #roster_version{}}.
diff --git a/src/mod_roster_sql.erl b/src/mod_roster_sql.erl
new file mode 100644
index 00000000..82662865
--- /dev/null
+++ b/src/mod_roster_sql.erl
@@ -0,0 +1,308 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_roster_sql).
+
+-behaviour(mod_roster).
+
+%% API
+-export([init/2, read_roster_version/2, write_roster_version/4,
+	 get_roster/2, get_roster_by_jid/3,
+	 roster_subscribe/4, get_roster_by_jid_with_groups/3,
+	 remove_user/2, update_roster/4, del_roster/3, transaction/2,
+	 read_subscription_and_groups/3, get_only_items/2,
+	 import/1, import/2, export/1]).
+
+-include("jlib.hrl").
+-include("mod_roster.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+read_roster_version(LUser, LServer) ->
+    case odbc_queries:get_roster_version(LServer, LUser) of
+	{selected, [{Version}]} -> Version;
+	{selected, []} -> error
+    end.
+
+write_roster_version(LUser, LServer, InTransaction, Ver) ->
+    Username = ejabberd_odbc:escape(LUser),
+    EVer = ejabberd_odbc:escape(Ver),
+    if InTransaction ->
+	    odbc_queries:set_roster_version(Username, EVer);
+       true ->
+	    odbc_queries:sql_transaction(
+	      LServer,
+	      fun () ->
+		      odbc_queries:set_roster_version(Username, EVer)
+	      end)
+    end.
+
+get_roster(LUser, LServer) ->
+    case catch odbc_queries:get_roster(LServer, LUser) of
+        {selected, Items} when is_list(Items) ->
+            JIDGroups = case catch odbc_queries:get_roster_jid_groups(
+                                     LServer, LUser) of
+                            {selected, JGrps} when is_list(JGrps) ->
+                                JGrps;
+                            _ ->
+				[]
+                        end,
+            GroupsDict = lists:foldl(fun({J, G}, Acc) ->
+                                             dict:append(J, G, Acc)
+                                     end,
+                                     dict:new(), JIDGroups),
+	    lists:flatmap(
+	      fun(I) ->
+		      case raw_to_record(LServer, I) of
+			  %% Bad JID in database:
+			  error -> [];
+			  R ->
+			      SJID = jid:to_string(R#roster.jid),
+			      Groups = case dict:find(SJID, GroupsDict) of
+					   {ok, Gs} -> Gs;
+					   error -> []
+				       end,
+			      [R#roster{groups = Groups}]
+		      end
+	      end, Items);
+        _ ->
+	    []
+    end.
+
+get_roster_by_jid(LUser, LServer, LJID) ->
+    {selected, Res} =
+	odbc_queries:get_roster_by_jid(LServer, LUser, jid:to_string(LJID)),
+    case Res of
+	[] ->
+	    #roster{usj = {LUser, LServer, LJID},
+		    us = {LUser, LServer}, jid = LJID};
+	[I] ->
+	    R = raw_to_record(LServer, I),
+	    case R of
+		%% Bad JID in database:
+		error ->
+		    #roster{usj = {LUser, LServer, LJID},
+			    us = {LUser, LServer}, jid = LJID};
+		_ ->
+		    R#roster{usj = {LUser, LServer, LJID},
+			     us = {LUser, LServer}, jid = LJID, name = <<"">>}
+	    end
+    end.
+
+get_only_items(LUser, LServer) ->
+    case catch odbc_queries:get_roster(LServer, LUser) of
+	{selected, Is} when is_list(Is) ->
+	    lists:map(fun(I) -> raw_to_record(LServer, I) end, Is);
+	_ -> []
+    end.
+
+roster_subscribe(_LUser, _LServer, _LJID, Item) ->
+    ItemVals = record_to_row(Item),
+    odbc_queries:roster_subscribe(ItemVals).
+
+transaction(LServer, F) ->
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+get_roster_by_jid_with_groups(LUser, LServer, LJID) ->
+    SJID = jid:to_string(LJID),
+    case odbc_queries:get_roster_by_jid(LServer, LUser, SJID) of
+	{selected, [I]} ->
+            R = raw_to_record(LServer, I),
+            Groups =
+                case odbc_queries:get_roster_groups(LServer, LUser, SJID) of
+                    {selected, JGrps} when is_list(JGrps) ->
+                        [JGrp || {JGrp} <- JGrps];
+                    _ -> []
+                end,
+            R#roster{groups = Groups};
+	{selected, []} ->
+	    #roster{usj = {LUser, LServer, LJID},
+		    us = {LUser, LServer}, jid = LJID}
+    end.
+
+remove_user(LUser, LServer) ->
+    odbc_queries:del_user_roster_t(LServer, LUser),
+    {atomic, ok}.
+
+update_roster(LUser, LServer, LJID, Item) ->
+    SJID = jid:to_string(LJID),
+    ItemVals = record_to_row(Item),
+    ItemGroups = Item#roster.groups,
+    odbc_queries:update_roster(LServer, LUser, SJID, ItemVals,
+                               ItemGroups).
+
+del_roster(LUser, LServer, LJID) ->
+    SJID = jid:to_string(LJID),
+    odbc_queries:del_roster(LServer, LUser, SJID).
+
+read_subscription_and_groups(LUser, LServer, LJID) ->
+    SJID = jid:to_string(LJID),
+    case catch odbc_queries:get_subscription(LServer, LUser, SJID) of
+	{selected, [{SSubscription}]} ->
+	    Subscription = case SSubscription of
+			       <<"B">> -> both;
+			       <<"T">> -> to;
+			       <<"F">> -> from;
+			       _ -> none
+			   end,
+	    Groups = case catch odbc_queries:get_rostergroup_by_jid(
+				  LServer, LUser, SJID) of
+			 {selected, JGrps} when is_list(JGrps) ->
+			     [JGrp || {JGrp} <- JGrps];
+			 _ -> []
+		     end,
+	    {Subscription, Groups};
+	_ ->
+	    error
+    end.
+
+export(_Server) ->
+    [{roster,
+      fun(Host, #roster{usj = {LUser, LServer, LJID}} = R)
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              SJID = ejabberd_odbc:escape(jid:to_string(LJID)),
+              ItemVals = record_to_string(R),
+              ItemGroups = groups_to_string(R),
+              odbc_queries:update_roster_sql(Username, SJID,
+                                             ItemVals, ItemGroups);
+        (_Host, _R) ->
+              []
+      end},
+     {roster_version,
+      fun(Host, #roster_version{us = {LUser, LServer}, version = Ver})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              SVer = ejabberd_odbc:escape(Ver),
+              [[<<"delete from roster_version where username='">>,
+                Username, <<"';">>],
+               [<<"insert into roster_version(username, version) values('">>,
+                Username, <<"', '">>, SVer, <<"');">>]];
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select username, jid, nick, subscription, "
+        "ask, askmessage, server, subscribe, type from rosterusers;">>,
+      fun([LUser, JID|_] = Row) ->
+              Item = raw_to_record(LServer, Row),
+              Username = ejabberd_odbc:escape(LUser),
+              SJID = ejabberd_odbc:escape(JID),
+              {selected, _, Rows} =
+                  ejabberd_odbc:sql_query_t(
+                    [<<"select grp from rostergroups where username='">>,
+                     Username, <<"' and jid='">>, SJID, <<"'">>]),
+              Groups = [Grp || [Grp] <- Rows],
+              Item#roster{groups = Groups}
+      end},
+     {<<"select username, version from roster_version;">>,
+      fun([LUser, Ver]) ->
+              #roster_version{us = {LUser, LServer}, version = Ver}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+raw_to_record(LServer,
+	      [User, SJID, Nick, SSubscription, SAsk, SAskMessage,
+	       _SServer, _SSubscribe, _SType]) ->
+    raw_to_record(LServer,
+                  {User, SJID, Nick, SSubscription, SAsk, SAskMessage,
+                   _SServer, _SSubscribe, _SType});
+raw_to_record(LServer,
+	      {User, SJID, Nick, SSubscription, SAsk, SAskMessage,
+	       _SServer, _SSubscribe, _SType}) ->
+    case jid:from_string(SJID) of
+      error -> error;
+      JID ->
+	  LJID = jid:tolower(JID),
+	  Subscription = case SSubscription of
+			   <<"B">> -> both;
+			   <<"T">> -> to;
+			   <<"F">> -> from;
+			   _ -> none
+			 end,
+	  Ask = case SAsk of
+		  <<"S">> -> subscribe;
+		  <<"U">> -> unsubscribe;
+		  <<"B">> -> both;
+		  <<"O">> -> out;
+		  <<"I">> -> in;
+		  _ -> none
+		end,
+	  #roster{usj = {User, LServer, LJID},
+		  us = {User, LServer}, jid = LJID, name = Nick,
+		  subscription = Subscription, ask = Ask,
+		  askmessage = SAskMessage}
+    end.
+
+record_to_string(#roster{us = {User, _Server},
+			 jid = JID, name = Name, subscription = Subscription,
+			 ask = Ask, askmessage = AskMessage}) ->
+    Username = ejabberd_odbc:escape(User),
+    SJID =
+	ejabberd_odbc:escape(jid:to_string(jid:tolower(JID))),
+    Nick = ejabberd_odbc:escape(Name),
+    SSubscription = case Subscription of
+		      both -> <<"B">>;
+		      to -> <<"T">>;
+		      from -> <<"F">>;
+		      none -> <<"N">>
+		    end,
+    SAsk = case Ask of
+	     subscribe -> <<"S">>;
+	     unsubscribe -> <<"U">>;
+	     both -> <<"B">>;
+	     out -> <<"O">>;
+	     in -> <<"I">>;
+	     none -> <<"N">>
+	   end,
+    SAskMessage = ejabberd_odbc:escape(AskMessage),
+    [Username, SJID, Nick, SSubscription, SAsk, SAskMessage,
+     <<"N">>, <<"">>, <<"item">>].
+
+record_to_row(
+  #roster{us = {LUser, _LServer},
+          jid = JID, name = Name, subscription = Subscription,
+          ask = Ask, askmessage = AskMessage}) ->
+    SJID = jid:to_string(jid:tolower(JID)),
+    SSubscription = case Subscription of
+		      both -> <<"B">>;
+		      to -> <<"T">>;
+		      from -> <<"F">>;
+		      none -> <<"N">>
+		    end,
+    SAsk = case Ask of
+	     subscribe -> <<"S">>;
+	     unsubscribe -> <<"U">>;
+	     both -> <<"B">>;
+	     out -> <<"O">>;
+	     in -> <<"I">>;
+	     none -> <<"N">>
+	   end,
+    {LUser, SJID, Name, SSubscription, SAsk, AskMessage}.
+
+groups_to_string(#roster{us = {User, _Server},
+			 jid = JID, groups = Groups}) ->
+    Username = ejabberd_odbc:escape(User),
+    SJID =
+	ejabberd_odbc:escape(jid:to_string(jid:tolower(JID))),
+    lists:foldl(fun (<<"">>, Acc) -> Acc;
+		    (Group, Acc) ->
+			G = ejabberd_odbc:escape(Group),
+			[[Username, SJID, G] | Acc]
+		end,
+		[], Groups).
diff --git a/src/mod_shared_roster.erl b/src/mod_shared_roster.erl
index 212a7d47..6670cf77 100644
--- a/src/mod_shared_roster.erl
+++ b/src/mod_shared_roster.erl
@@ -38,7 +38,7 @@
 	 list_groups/1, create_group/2, create_group/3,
 	 delete_group/2, get_group_opts/2, set_group_opts/3,
 	 get_group_users/2, get_group_explicit_users/2,
-	 is_user_in_group/3, add_user_to_group/3,
+	 is_user_in_group/3, add_user_to_group/3, opts_to_binary/1,
 	 remove_user_from_group/3, mod_opt_type/1]).
 
 -include("ejabberd.hrl").
@@ -52,25 +52,28 @@
 
 -include("ejabberd_web_admin.hrl").
 
--record(sr_group, {group_host = {<<"">>, <<"">>} :: {'$1' | binary(), '$2' | binary()},
-                   opts = [] :: list() | '_' | '$2'}).
-
--record(sr_user, {us = {<<"">>, <<"">>} :: {binary(), binary()},
-                  group_host = {<<"">>, <<"">>} :: {binary(), binary()}}).
+-include("mod_shared_roster.hrl").
+
+-type group_options() :: [{atom(), any()}].
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #sr_user{} | #sr_group{}) -> ok | pass.
+-callback list_groups(binary()) -> [binary()].
+-callback groups_with_opts(binary()) -> [{binary(), group_options()}].
+-callback create_group(binary(), binary(), group_options()) -> {atomic, any()}.
+-callback delete_group(binary(), binary()) -> {atomic, any()}.
+-callback get_group_opts(binary(), binary()) -> group_options() | error.
+-callback set_group_opts(binary(), binary(), group_options()) -> {atomic, any()}.
+-callback get_user_groups({binary(), binary()}, binary()) -> [binary()].
+-callback get_group_explicit_users(binary(), binary()) -> [{binary(), binary()}].
+-callback get_user_displayed_groups(binary(), binary(), group_options()) ->
+    [{binary(), group_options()}].
+-callback is_user_in_group({binary(), binary()}, binary(), binary()) -> boolean().
+-callback add_user_to_group(binary(), {binary(), binary()}, binary()) -> {atomic, any()}.
+-callback remove_user_from_group(binary(), {binary(), binary()}, binary()) -> {atomic, any()}.
 
 start(Host, Opts) ->
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(sr_group,
-			      [{disc_copies, [node()]},
-			       {attributes, record_info(fields, sr_group)}]),
-	  mnesia:create_table(sr_user,
-			      [{disc_copies, [node()]}, {type, bag},
-			       {attributes, record_info(fields, sr_user)}]),
-          update_tables(),
-	  mnesia:add_table_index(sr_user, group_host);
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     ejabberd_hooks:add(webadmin_menu_host, Host, ?MODULE,
 		       webadmin_menu, 70),
     ejabberd_hooks:add(webadmin_page_host, Host, ?MODULE,
@@ -391,195 +394,36 @@ process_subscription(Direction, User, Server, JID,
     end.
 
 list_groups(Host) ->
-    list_groups(Host, gen_mod:db_type(Host, ?MODULE)).
-
-list_groups(Host, mnesia) ->
-    mnesia:dirty_select(sr_group,
-			[{#sr_group{group_host = {'$1', '$2'}, _ = '_'},
-			  [{'==', '$2', Host}], ['$1']}]);
-list_groups(Host, riak) ->
-    case ejabberd_riak:get_keys_by_index(sr_group, <<"host">>, Host) of
-        {ok, Gs} ->
-            [G || {G, _} <- Gs];
-        _ ->
-            []
-    end;
-list_groups(Host, odbc) ->
-    case ejabberd_odbc:sql_query(Host,
-				 [<<"select name from sr_group;">>])
-	of
-      {selected, [<<"name">>], Rs} -> [G || [G] <- Rs];
-      _ -> []
-    end.
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:list_groups(Host).
 
 groups_with_opts(Host) ->
-    groups_with_opts(Host, gen_mod:db_type(Host, ?MODULE)).
-
-groups_with_opts(Host, mnesia) ->
-    Gs = mnesia:dirty_select(sr_group,
-			     [{#sr_group{group_host = {'$1', Host}, opts = '$2',
-					 _ = '_'},
-			       [], [['$1', '$2']]}]),
-    lists:map(fun ([G, O]) -> {G, O} end, Gs);
-groups_with_opts(Host, riak) ->
-    case ejabberd_riak:get_by_index(sr_group, sr_group_schema(),
-				    <<"host">>, Host) of
-        {ok, Rs} ->
-            [{G, O} || #sr_group{group_host = {G, _}, opts = O} <- Rs];
-        _ ->
-            []
-    end;
-groups_with_opts(Host, odbc) ->
-    case ejabberd_odbc:sql_query(Host,
-				 [<<"select name, opts from sr_group;">>])
-	of
-      {selected, [<<"name">>, <<"opts">>], Rs} ->
-	  [{G, opts_to_binary(ejabberd_odbc:decode_term(Opts))}
-	   || [G, Opts] <- Rs];
-      _ -> []
-    end.
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:groups_with_opts(Host).
 
 create_group(Host, Group) ->
     create_group(Host, Group, []).
 
 create_group(Host, Group, Opts) ->
-    create_group(Host, Group, Opts,
-		 gen_mod:db_type(Host, ?MODULE)).
-
-create_group(Host, Group, Opts, mnesia) ->
-    R = #sr_group{group_host = {Group, Host}, opts = Opts},
-    F = fun () -> mnesia:write(R) end,
-    mnesia:transaction(F);
-create_group(Host, Group, Opts, riak) ->
-    {atomic, ejabberd_riak:put(#sr_group{group_host = {Group, Host},
-                                         opts = Opts},
-			       sr_group_schema(),
-                               [{'2i', [{<<"host">>, Host}]}])};
-create_group(Host, Group, Opts, odbc) ->
-    SGroup = ejabberd_odbc:escape(Group),
-    SOpts = ejabberd_odbc:encode_term(Opts),
-    F = fun () ->
-		odbc_queries:update_t(<<"sr_group">>,
-				      [<<"name">>, <<"opts">>], [SGroup, SOpts],
-				      [<<"name='">>, SGroup, <<"'">>])
-	end,
-    ejabberd_odbc:sql_transaction(Host, F).
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:create_group(Host, Group, Opts).
 
 delete_group(Host, Group) ->
-    delete_group(Host, Group,
-		 gen_mod:db_type(Host, ?MODULE)).
-
-delete_group(Host, Group, mnesia) ->
-    GroupHost = {Group, Host},
-    F = fun () ->
-		mnesia:delete({sr_group, GroupHost}),
-		Users = mnesia:index_read(sr_user, GroupHost,
-					  #sr_user.group_host),
-		lists:foreach(fun (UserEntry) ->
-				      mnesia:delete_object(UserEntry)
-			      end,
-			      Users)
-	end,
-    mnesia:transaction(F);
-delete_group(Host, Group, riak) ->
-    try
-        ok = ejabberd_riak:delete(sr_group, {Group, Host}),
-        ok = ejabberd_riak:delete_by_index(sr_user, <<"group_host">>,
-                                           {Group, Host}),
-        {atomic, ok}
-    catch _:{badmatch, Err} ->
-            {atomic, Err}
-    end;
-delete_group(Host, Group, odbc) ->
-    SGroup = ejabberd_odbc:escape(Group),
-    F = fun () ->
-		ejabberd_odbc:sql_query_t([<<"delete from sr_group where name='">>,
-					   SGroup, <<"';">>]),
-		ejabberd_odbc:sql_query_t([<<"delete from sr_user where grp='">>,
-					   SGroup, <<"';">>])
-	end,
-    case ejabberd_odbc:sql_transaction(Host, F) of
-        {atomic,{updated,_}} -> {atomic, ok};
-        Res -> Res
-    end.
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:delete_group(Host, Group).
 
 get_group_opts(Host, Group) ->
-    get_group_opts(Host, Group,
-		   gen_mod:db_type(Host, ?MODULE)).
-
-get_group_opts(Host, Group, mnesia) ->
-    case catch mnesia:dirty_read(sr_group, {Group, Host}) of
-      [#sr_group{opts = Opts}] -> Opts;
-      _ -> error
-    end;
-get_group_opts(Host, Group, riak) ->
-    case ejabberd_riak:get(sr_group, sr_group_schema(), {Group, Host}) of
-        {ok, #sr_group{opts = Opts}} -> Opts;
-        _ -> error
-    end;
-get_group_opts(Host, Group, odbc) ->
-    SGroup = ejabberd_odbc:escape(Group),
-    case catch ejabberd_odbc:sql_query(Host,
-				       [<<"select opts from sr_group where name='">>,
-					SGroup, <<"';">>])
-	of
-      {selected, [<<"opts">>], [[SOpts]]} ->
-	  opts_to_binary(ejabberd_odbc:decode_term(SOpts));
-      _ -> error
-    end.
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:get_group_opts(Host, Group).
 
 set_group_opts(Host, Group, Opts) ->
-    set_group_opts(Host, Group, Opts,
-		   gen_mod:db_type(Host, ?MODULE)).
-
-set_group_opts(Host, Group, Opts, mnesia) ->
-    R = #sr_group{group_host = {Group, Host}, opts = Opts},
-    F = fun () -> mnesia:write(R) end,
-    mnesia:transaction(F);
-set_group_opts(Host, Group, Opts, riak) ->
-    {atomic, ejabberd_riak:put(#sr_group{group_host = {Group, Host},
-                                         opts = Opts},
-			       sr_group_schema(),
-                               [{'2i', [{<<"host">>, Host}]}])};
-set_group_opts(Host, Group, Opts, odbc) ->
-    SGroup = ejabberd_odbc:escape(Group),
-    SOpts = ejabberd_odbc:encode_term(Opts),
-    F = fun () ->
-		odbc_queries:update_t(<<"sr_group">>,
-				      [<<"name">>, <<"opts">>], [SGroup, SOpts],
-				      [<<"name='">>, SGroup, <<"'">>])
-	end,
-    ejabberd_odbc:sql_transaction(Host, F).
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:set_group_opts(Host, Group, Opts).
 
 get_user_groups(US) ->
     Host = element(2, US),
-    DBType = gen_mod:db_type(Host, ?MODULE),
-    get_user_groups(US, Host, DBType) ++
-      get_special_users_groups(Host).
-
-get_user_groups(US, Host, mnesia) ->
-    case catch mnesia:dirty_read(sr_user, US) of
-      Rs when is_list(Rs) ->
-	  [Group
-	   || #sr_user{group_host = {Group, H}} <- Rs, H == Host];
-      _ -> []
-    end;
-get_user_groups(US, Host, riak) ->
-    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(), <<"us">>, US) of
-        {ok, Rs} ->
-            [Group || #sr_user{group_host = {Group, H}} <- Rs, H == Host];
-        _ ->
-            []
-    end;
-get_user_groups(US, Host, odbc) ->
-    SJID = make_jid_s(US),
-    case catch ejabberd_odbc:sql_query(Host,
-				       [<<"select grp from sr_user where jid='">>,
-					SJID, <<"';">>])
-	of
-      {selected, [<<"grp">>], Rs} -> [G || [G] <- Rs];
-      _ -> []
-    end.
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:get_user_groups(US, Host) ++ get_special_users_groups(Host).
 
 is_group_enabled(Host1, Group1) ->
     {Host, Group} = split_grouphost(Host1, Group1),
@@ -630,39 +474,8 @@ get_group_users(Host, Group, GroupOpts) ->
 	++ get_group_explicit_users(Host, Group).
 
 get_group_explicit_users(Host, Group) ->
-    get_group_explicit_users(Host, Group,
-			     gen_mod:db_type(Host, ?MODULE)).
-
-get_group_explicit_users(Host, Group, mnesia) ->
-    Read = (catch mnesia:dirty_index_read(sr_user,
-					  {Group, Host}, #sr_user.group_host)),
-    case Read of
-      Rs when is_list(Rs) -> [R#sr_user.us || R <- Rs];
-      _ -> []
-    end;
-get_group_explicit_users(Host, Group, riak) ->
-    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(),
-				    <<"group_host">>, {Group, Host}) of
-        {ok, Rs} ->
-            [R#sr_user.us || R <- Rs];
-        _ ->
-            []
-    end;
-get_group_explicit_users(Host, Group, odbc) ->
-    SGroup = ejabberd_odbc:escape(Group),
-    case catch ejabberd_odbc:sql_query(Host,
-				       [<<"select jid from sr_user where grp='">>,
-					SGroup, <<"';">>])
-	of
-      {selected, [<<"jid">>], Rs} ->
-	  lists:map(fun ([JID]) ->
-			    {U, S, _} =
-				jid:tolower(jid:from_string(JID)),
-			    {U, S}
-		    end,
-		    Rs);
-      _ -> []
-    end.
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    Mod:get_group_explicit_users(Host, Group).
 
 get_group_name(Host1, Group1) ->
     {Host, Group} = split_grouphost(Host1, Group1),
@@ -718,44 +531,10 @@ get_special_displayed_groups(GroupsOpts) ->
 %% for the list of groups of that server that user is member
 %% get the list of groups displayed
 get_user_displayed_groups(LUser, LServer, GroupsOpts) ->
-    Groups = get_user_displayed_groups(LUser, LServer,
-				       GroupsOpts,
-				       gen_mod:db_type(LServer, ?MODULE)),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Groups = Mod:get_user_displayed_groups(LUser, LServer, GroupsOpts),
     displayed_groups(GroupsOpts, Groups).
 
-get_user_displayed_groups(LUser, LServer, GroupsOpts,
-			  mnesia) ->
-    case catch mnesia:dirty_read(sr_user, {LUser, LServer})
-	of
-      Rs when is_list(Rs) ->
-	  [{Group, proplists:get_value(Group, GroupsOpts, [])}
-	   || #sr_user{group_host = {Group, H}} <- Rs,
-	      H == LServer];
-      _ -> []
-    end;
-get_user_displayed_groups(LUser, LServer, GroupsOpts,
-                          riak) ->
-    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(),
-                                    <<"us">>, {LUser, LServer}) of
-        {ok, Rs} ->
-            [{Group, proplists:get_value(Group, GroupsOpts, [])}
-             || #sr_user{group_host = {Group, _}} <- Rs];
-        _ ->
-            []
-    end;
-get_user_displayed_groups(LUser, LServer, GroupsOpts,
-			  odbc) ->
-    SJID = make_jid_s(LUser, LServer),
-    case catch ejabberd_odbc:sql_query(LServer,
-				       [<<"select grp from sr_user where jid='">>,
-					SJID, <<"';">>])
-	of
-      {selected, [<<"grp">>], Rs} ->
-	  [{Group, proplists:get_value(Group, GroupsOpts, [])}
-	   || [Group] <- Rs];
-      _ -> []
-    end.
-
 %% @doc Get the list of groups that are displayed to this user
 get_user_displayed_groups(US) ->
     Host = element(2, US),
@@ -779,42 +558,12 @@ get_user_displayed_groups(US) ->
 	is_group_enabled(Host, Group)].
 
 is_user_in_group(US, Group, Host) ->
-    is_user_in_group(US, Group, Host,
-		     gen_mod:db_type(Host, ?MODULE)).
-
-is_user_in_group(US, Group, Host, mnesia) ->
-    case catch mnesia:dirty_match_object(#sr_user{us = US,
-						  group_host = {Group, Host}})
-	of
-      [] -> lists:member(US, get_group_users(Host, Group));
-      _ -> true
-    end;
-is_user_in_group(US, Group, Host, riak) ->
-    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(), <<"us">>, US) of
-        {ok, Rs} ->
-            case lists:any(
-                   fun(#sr_user{group_host = {G, H}}) ->
-                           (Group == G) and (Host == H)
-                   end, Rs) of
-                false ->
-                    lists:member(US, get_group_users(Host, Group));
-                true ->
-                    true
-            end;
-        _Err ->
-            false
-    end;
-is_user_in_group(US, Group, Host, odbc) ->
-    SJID = make_jid_s(US),
-    SGroup = ejabberd_odbc:escape(Group),
-    case catch ejabberd_odbc:sql_query(Host,
-				       [<<"select * from sr_user where jid='">>,
-					SJID, <<"' and grp='">>, SGroup,
-					<<"';">>])
-	of
-      {selected, _, []} ->
-	  lists:member(US, get_group_users(Host, Group));
-      _ -> true
+    Mod = gen_mod:db_mod(Host, ?MODULE),
+    case Mod:is_user_in_group(US, Group, Host) of
+	false ->
+	    lists:member(US, get_group_users(Host, Group));
+	true ->
+	    true
     end.
 
 %% @spec (Host::string(), {User::string(), Server::string()}, Group::string()) -> {atomic, ok}
@@ -837,31 +586,10 @@ add_user_to_group(Host, US, Group) ->
 	  push_displayed_to_user(LUser, LServer, Host, both, DisplayedGroups),
 	  broadcast_user_to_displayed(LUser, LServer, Host, both, DisplayedToGroups),
 	  broadcast_displayed_to_user(LUser, LServer, Host, both, DisplayedGroups),
-	  add_user_to_group(Host, US, Group, gen_mod:db_type(Host, ?MODULE))
+	  Mod = gen_mod:db_mod(Host, ?MODULE),
+	  Mod:add_user_to_group(Host, US, Group)
     end.
 
-add_user_to_group(Host, US, Group, mnesia) ->
-    R = #sr_user{us = US, group_host = {Group, Host}},
-    F = fun () -> mnesia:write(R) end,
-    mnesia:transaction(F);
-add_user_to_group(Host, US, Group, riak) ->
-    {atomic, ejabberd_riak:put(
-               #sr_user{us = US, group_host = {Group, Host}},
-	       sr_user_schema(),
-               [{i, {US, {Group, Host}}},
-                {'2i', [{<<"us">>, US},
-                        {<<"group_host">>, {Group, Host}}]}])};
-add_user_to_group(Host, US, Group, odbc) ->
-    SJID = make_jid_s(US),
-    SGroup = ejabberd_odbc:escape(Group),
-    F = fun () ->
-		odbc_queries:update_t(<<"sr_user">>,
-				      [<<"jid">>, <<"grp">>], [SJID, SGroup],
-				      [<<"jid='">>, SJID, <<"' and grp='">>,
-				       SGroup, <<"'">>])
-	end,
-    ejabberd_odbc:sql_transaction(Host, F).
-
 get_displayed_groups(Group, LServer) ->
     GroupsOpts = groups_with_opts(LServer),
     GroupOpts = proplists:get_value(Group, GroupsOpts, []),
@@ -894,8 +622,8 @@ remove_user_from_group(Host, US, Group) ->
 			 end,
 	  (?MODULE):set_group_opts(Host, Group, NewGroupOpts);
       nomatch ->
-	  Result = remove_user_from_group(Host, US, Group,
-					  gen_mod:db_type(Host, ?MODULE)),
+	  Mod = gen_mod:db_mod(Host, ?MODULE),
+	  Result = Mod:remove_user_from_group(Host, US, Group),
 	  DisplayedToGroups = displayed_to_groups(Group, Host),
 	  DisplayedGroups = get_displayed_groups(Group, LServer),
 	  push_user_to_displayed(LUser, LServer, Group, Host, remove, DisplayedToGroups),
@@ -903,23 +631,6 @@ remove_user_from_group(Host, US, Group) ->
 	  Result
     end.
 
-remove_user_from_group(Host, US, Group, mnesia) ->
-    R = #sr_user{us = US, group_host = {Group, Host}},
-    F = fun () -> mnesia:delete_object(R) end,
-    mnesia:transaction(F);
-remove_user_from_group(Host, US, Group, riak) ->
-    {atomic, ejabberd_riak:delete(sr_group, {US, {Group, Host}})};
-remove_user_from_group(Host, US, Group, odbc) ->
-    SJID = make_jid_s(US),
-    SGroup = ejabberd_odbc:escape(Group),
-    F = fun () ->
-		ejabberd_odbc:sql_query_t([<<"delete from sr_user where jid='">>,
-					   SJID, <<"' and grp='">>, SGroup,
-					   <<"';">>]),
-		ok
-	end,
-    ejabberd_odbc:sql_transaction(Host, F).
-
 push_members_to_user(LUser, LServer, Group, Host,
 		     Subscription) ->
     GroupsOpts = groups_with_opts(LServer),
@@ -1385,13 +1096,6 @@ displayed_groups_update(Members, DisplayedGroups, Subscription) ->
 	    end
 	end, Members).
 
-make_jid_s(U, S) ->
-    ejabberd_odbc:escape(jid:to_string(jid:tolower(jid:make(U,
-									   S,
-									   <<"">>)))).
-
-make_jid_s({U, S}) -> make_jid_s(U, S).
-
 opts_to_binary(Opts) ->
     lists:map(
       fun({name, Name}) ->
@@ -1404,105 +1108,17 @@ opts_to_binary(Opts) ->
               Opt
       end, Opts).
 
-sr_group_schema() ->
-    {record_info(fields, sr_group), #sr_group{}}.
-
-sr_user_schema() ->
-    {record_info(fields, sr_user), #sr_user{}}.
-
-update_tables() ->
-    update_sr_group_table(),
-    update_sr_user_table().
-
-update_sr_group_table() ->
-    Fields = record_info(fields, sr_group),
-    case mnesia:table_info(sr_group, attributes) of
-        Fields ->
-            ejabberd_config:convert_table_to_binary(
-              sr_group, Fields, set,
-              fun(#sr_group{group_host = {G, _}}) -> G end,
-              fun(#sr_group{group_host = {G, H},
-                            opts = Opts} = R) ->
-                      R#sr_group{group_host = {iolist_to_binary(G),
-                                               iolist_to_binary(H)},
-                                 opts = opts_to_binary(Opts)}
-              end);
-        _ ->
-            ?INFO_MSG("Recreating sr_group table", []),
-            mnesia:transform_table(sr_group, ignore, Fields)
-    end.
-
-update_sr_user_table() ->
-    Fields = record_info(fields, sr_user),
-    case mnesia:table_info(sr_user, attributes) of
-        Fields ->
-            ejabberd_config:convert_table_to_binary(
-              sr_user, Fields, bag,
-              fun(#sr_user{us = {U, _}}) -> U end,
-              fun(#sr_user{us = {U, S}, group_host = {G, H}} = R) ->
-                      R#sr_user{us = {iolist_to_binary(U), iolist_to_binary(S)},
-                                group_host = {iolist_to_binary(G),
-                                              iolist_to_binary(H)}}
-              end);
-        _ ->
-            ?INFO_MSG("Recreating sr_user table", []),
-            mnesia:transform_table(sr_user, ignore, Fields)
-    end.
-
-export(_Server) ->
-    [{sr_group,
-      fun(Host, #sr_group{group_host = {Group, LServer}, opts = Opts})
-            when LServer == Host ->
-              SGroup = ejabberd_odbc:escape(Group),
-              SOpts = ejabberd_odbc:encode_term(Opts),
-              [[<<"delete from sr_group where name='">>, Group, <<"';">>],
-               [<<"insert into sr_group(name, opts) values ('">>,
-                SGroup, <<"', '">>, SOpts, <<"');">>]];
-         (_Host, _R) ->
-              []
-      end},
-     {sr_user,
-      fun(Host, #sr_user{us = {U, S}, group_host = {Group, LServer}})
-            when LServer == Host ->
-              SGroup = ejabberd_odbc:escape(Group),
-              SJID = ejabberd_odbc:escape(
-                       jid:to_string(
-                         jid:tolower(
-                           jid:make(U, S, <<"">>)))),
-              [[<<"delete from sr_user where jid='">>, SJID,
-                <<"'and grp='">>, Group, <<"';">>],
-               [<<"insert into sr_user(jid, grp) values ('">>,
-                SJID, <<"', '">>, SGroup, <<"');">>]];
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select name, opts from sr_group;">>,
-      fun([Group, SOpts]) ->
-              #sr_group{group_host = {Group, LServer},
-                        opts = ejabberd_odbc:decode_term(SOpts)}
-      end},
-     {<<"select jid, grp from sr_user;">>,
-      fun([SJID, Group]) ->
-              #jid{luser = U, lserver = S} = jid:from_string(SJID),
-              #sr_user{us = {U, S}, group_host = {Group, LServer}}
-      end}].
-
-import(_LServer, mnesia, #sr_group{} = G) ->
-    mnesia:dirty_write(G);
-
-import(_LServer, mnesia, #sr_user{} = U) ->
-    mnesia:dirty_write(U);
-import(_LServer, riak, #sr_group{group_host = {_, Host}} = G) ->
-    ejabberd_riak:put(G, sr_group_schema(), [{'2i', [{<<"host">>, Host}]}]);
-import(_LServer, riak, #sr_user{us = US, group_host = {Group, Host}} = User) ->
-    ejabberd_riak:put(User, sr_user_schema(),
-                      [{i, {US, {Group, Host}}},
-                       {'2i', [{<<"us">>, US},
-                               {<<"group_host">>, {Group, Host}}]}]);
-import(_, _, _) ->
-    pass.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
+
+import(LServer, DBType, Data) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, Data).
 
 mod_opt_type(db_type) -> fun gen_mod:v_db/1;
 mod_opt_type(_) -> [db_type].
diff --git a/src/mod_shared_roster_mnesia.erl b/src/mod_shared_roster_mnesia.erl
new file mode 100644
index 00000000..ca2e55e2
--- /dev/null
+++ b/src/mod_shared_roster_mnesia.erl
@@ -0,0 +1,167 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_shared_roster_mnesia).
+
+-behaviour(mod_shared_roster).
+
+%% API
+-export([init/2, list_groups/1, groups_with_opts/1, create_group/3,
+	 delete_group/2, get_group_opts/2, set_group_opts/3,
+	 get_user_groups/2, get_group_explicit_users/2,
+	 get_user_displayed_groups/3, is_user_in_group/3,
+	 add_user_to_group/3, remove_user_from_group/3, import/2]).
+
+-include("jlib.hrl").
+-include("mod_roster.hrl").
+-include("mod_shared_roster.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(sr_group,
+			[{disc_copies, [node()]},
+			 {attributes, record_info(fields, sr_group)}]),
+    mnesia:create_table(sr_user,
+			[{disc_copies, [node()]}, {type, bag},
+			 {attributes, record_info(fields, sr_user)}]),
+    update_tables(),
+    mnesia:add_table_index(sr_user, group_host).
+
+list_groups(Host) ->
+    mnesia:dirty_select(sr_group,
+			[{#sr_group{group_host = {'$1', '$2'}, _ = '_'},
+			  [{'==', '$2', Host}], ['$1']}]).
+
+groups_with_opts(Host) ->
+    Gs = mnesia:dirty_select(sr_group,
+			     [{#sr_group{group_host = {'$1', Host}, opts = '$2',
+					 _ = '_'},
+			       [], [['$1', '$2']]}]),
+    lists:map(fun ([G, O]) -> {G, O} end, Gs).
+
+create_group(Host, Group, Opts) ->
+    R = #sr_group{group_host = {Group, Host}, opts = Opts},
+    F = fun () -> mnesia:write(R) end,
+    mnesia:transaction(F).
+
+delete_group(Host, Group) ->
+    GroupHost = {Group, Host},
+    F = fun () ->
+		mnesia:delete({sr_group, GroupHost}),
+		Users = mnesia:index_read(sr_user, GroupHost,
+					  #sr_user.group_host),
+		lists:foreach(fun (UserEntry) ->
+				      mnesia:delete_object(UserEntry)
+			      end,
+			      Users)
+	end,
+    mnesia:transaction(F).
+
+get_group_opts(Host, Group) ->
+    case catch mnesia:dirty_read(sr_group, {Group, Host}) of
+	[#sr_group{opts = Opts}] -> Opts;
+	_ -> error
+    end.
+
+set_group_opts(Host, Group, Opts) ->
+    R = #sr_group{group_host = {Group, Host}, opts = Opts},
+    F = fun () -> mnesia:write(R) end,
+    mnesia:transaction(F).
+
+get_user_groups(US, Host) ->
+    case catch mnesia:dirty_read(sr_user, US) of
+	Rs when is_list(Rs) ->
+	    [Group || #sr_user{group_host = {Group, H}} <- Rs, H == Host];
+	_ ->
+	    []
+    end.
+
+get_group_explicit_users(Host, Group) ->
+    Read = (catch mnesia:dirty_index_read(sr_user,
+					  {Group, Host}, #sr_user.group_host)),
+    case Read of
+	Rs when is_list(Rs) -> [R#sr_user.us || R <- Rs];
+	_ -> []
+    end.
+
+get_user_displayed_groups(LUser, LServer, GroupsOpts) ->
+    case catch mnesia:dirty_read(sr_user, {LUser, LServer}) of
+	Rs when is_list(Rs) ->
+	    [{Group, proplists:get_value(Group, GroupsOpts, [])}
+	     || #sr_user{group_host = {Group, H}} <- Rs,
+		H == LServer];
+	_ ->
+	    []
+    end.
+
+is_user_in_group(US, Group, Host) ->
+    case mnesia:dirty_match_object(
+	   #sr_user{us = US, group_host = {Group, Host}}) of
+	[] -> false;
+	_ -> true
+    end.
+
+add_user_to_group(Host, US, Group) ->
+    R = #sr_user{us = US, group_host = {Group, Host}},
+    F = fun () -> mnesia:write(R) end,
+    mnesia:transaction(F).
+
+remove_user_from_group(Host, US, Group) ->
+    R = #sr_user{us = US, group_host = {Group, Host}},
+    F = fun () -> mnesia:delete_object(R) end,
+    mnesia:transaction(F).
+
+import(_LServer, #sr_group{} = G) ->
+    mnesia:dirty_write(G);
+import(_LServer, #sr_user{} = U) ->
+    mnesia:dirty_write(U).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_tables() ->
+    update_sr_group_table(),
+    update_sr_user_table().
+
+update_sr_group_table() ->
+    Fields = record_info(fields, sr_group),
+    case mnesia:table_info(sr_group, attributes) of
+        Fields ->
+            ejabberd_config:convert_table_to_binary(
+              sr_group, Fields, set,
+              fun(#sr_group{group_host = {G, _}}) -> G end,
+              fun(#sr_group{group_host = {G, H},
+                            opts = Opts} = R) ->
+                      R#sr_group{group_host = {iolist_to_binary(G),
+                                               iolist_to_binary(H)},
+                                 opts = mod_shared_roster:opts_to_binary(Opts)}
+              end);
+        _ ->
+            ?INFO_MSG("Recreating sr_group table", []),
+            mnesia:transform_table(sr_group, ignore, Fields)
+    end.
+
+update_sr_user_table() ->
+    Fields = record_info(fields, sr_user),
+    case mnesia:table_info(sr_user, attributes) of
+        Fields ->
+            ejabberd_config:convert_table_to_binary(
+              sr_user, Fields, bag,
+              fun(#sr_user{us = {U, _}}) -> U end,
+              fun(#sr_user{us = {U, S}, group_host = {G, H}} = R) ->
+                      R#sr_user{us = {iolist_to_binary(U), iolist_to_binary(S)},
+                                group_host = {iolist_to_binary(G),
+                                              iolist_to_binary(H)}}
+              end);
+        _ ->
+            ?INFO_MSG("Recreating sr_user table", []),
+            mnesia:transform_table(sr_user, ignore, Fields)
+    end.
diff --git a/src/mod_shared_roster_riak.erl b/src/mod_shared_roster_riak.erl
new file mode 100644
index 00000000..0df35e37
--- /dev/null
+++ b/src/mod_shared_roster_riak.erl
@@ -0,0 +1,139 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_shared_roster_riak).
+
+-behaviour(mod_shared_roster).
+
+%% API
+-export([init/2, list_groups/1, groups_with_opts/1, create_group/3,
+	 delete_group/2, get_group_opts/2, set_group_opts/3,
+	 get_user_groups/2, get_group_explicit_users/2,
+	 get_user_displayed_groups/3, is_user_in_group/3,
+	 add_user_to_group/3, remove_user_from_group/3, import/2]).
+
+-include("jlib.hrl").
+-include("mod_roster.hrl").
+-include("mod_shared_roster.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+list_groups(Host) ->
+    case ejabberd_riak:get_keys_by_index(sr_group, <<"host">>, Host) of
+        {ok, Gs} ->
+            [G || {G, _} <- Gs];
+        _ ->
+            []
+    end.
+
+groups_with_opts(Host) ->
+    case ejabberd_riak:get_by_index(sr_group, sr_group_schema(),
+				    <<"host">>, Host) of
+        {ok, Rs} ->
+            [{G, O} || #sr_group{group_host = {G, _}, opts = O} <- Rs];
+        _ ->
+            []
+    end.
+
+create_group(Host, Group, Opts) ->
+    {atomic, ejabberd_riak:put(#sr_group{group_host = {Group, Host},
+                                         opts = Opts},
+			       sr_group_schema(),
+                               [{'2i', [{<<"host">>, Host}]}])}.
+
+delete_group(Host, Group) ->
+    try
+        ok = ejabberd_riak:delete(sr_group, {Group, Host}),
+        ok = ejabberd_riak:delete_by_index(sr_user, <<"group_host">>,
+                                           {Group, Host}),
+        {atomic, ok}
+    catch _:{badmatch, Err} ->
+            {atomic, Err}
+    end.
+
+get_group_opts(Host, Group) ->
+    case ejabberd_riak:get(sr_group, sr_group_schema(), {Group, Host}) of
+        {ok, #sr_group{opts = Opts}} -> Opts;
+        _ -> error
+    end.
+
+set_group_opts(Host, Group, Opts) ->
+    {atomic, ejabberd_riak:put(#sr_group{group_host = {Group, Host},
+                                         opts = Opts},
+			       sr_group_schema(),
+                               [{'2i', [{<<"host">>, Host}]}])}.
+
+get_user_groups(US, Host) ->
+    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(), <<"us">>, US) of
+        {ok, Rs} ->
+            [Group || #sr_user{group_host = {Group, H}} <- Rs, H == Host];
+        _ ->
+            []
+    end.
+
+get_group_explicit_users(Host, Group) ->
+    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(),
+				    <<"group_host">>, {Group, Host}) of
+        {ok, Rs} ->
+            [R#sr_user.us || R <- Rs];
+        _ ->
+            []
+    end.
+
+get_user_displayed_groups(LUser, LServer, GroupsOpts) ->
+    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(),
+                                    <<"us">>, {LUser, LServer}) of
+        {ok, Rs} ->
+            [{Group, proplists:get_value(Group, GroupsOpts, [])}
+             || #sr_user{group_host = {Group, _}} <- Rs];
+        _ ->
+            []
+    end.
+
+is_user_in_group(US, Group, Host) ->
+    case ejabberd_riak:get_by_index(sr_user, sr_user_schema(), <<"us">>, US) of
+        {ok, Rs} ->
+            lists:any(
+	      fun(#sr_user{group_host = {G, H}}) ->
+		      (Group == G) and (Host == H)
+	      end, Rs);
+        _Err ->
+            false
+    end.
+
+add_user_to_group(Host, US, Group) ->
+    {atomic, ejabberd_riak:put(
+               #sr_user{us = US, group_host = {Group, Host}},
+	       sr_user_schema(),
+               [{i, {US, {Group, Host}}},
+                {'2i', [{<<"us">>, US},
+                        {<<"group_host">>, {Group, Host}}]}])}.
+
+remove_user_from_group(Host, US, Group) ->
+    {atomic, ejabberd_riak:delete(sr_group, {US, {Group, Host}})}.
+
+import(_LServer, #sr_group{group_host = {_, Host}} = G) ->
+    ejabberd_riak:put(G, sr_group_schema(), [{'2i', [{<<"host">>, Host}]}]);
+import(_LServer, #sr_user{us = US, group_host = {Group, Host}} = User) ->
+    ejabberd_riak:put(User, sr_user_schema(),
+                      [{i, {US, {Group, Host}}},
+                       {'2i', [{<<"us">>, US},
+                               {<<"group_host">>, {Group, Host}}]}]).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+sr_group_schema() ->
+    {record_info(fields, sr_group), #sr_group{}}.
+
+sr_user_schema() ->
+    {record_info(fields, sr_user), #sr_user{}}.
diff --git a/src/mod_shared_roster_sql.erl b/src/mod_shared_roster_sql.erl
new file mode 100644
index 00000000..21ea768a
--- /dev/null
+++ b/src/mod_shared_roster_sql.erl
@@ -0,0 +1,212 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 14 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_shared_roster_sql).
+
+-behaviour(mod_shared_roster).
+
+%% API
+-export([init/2, list_groups/1, groups_with_opts/1, create_group/3,
+	 delete_group/2, get_group_opts/2, set_group_opts/3,
+	 get_user_groups/2, get_group_explicit_users/2,
+	 get_user_displayed_groups/3, is_user_in_group/3,
+	 add_user_to_group/3, remove_user_from_group/3, import/1,
+	 import/2, export/1]).
+
+-include("jlib.hrl").
+-include("mod_roster.hrl").
+-include("mod_shared_roster.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+list_groups(Host) ->
+    case ejabberd_odbc:sql_query(
+	   Host, [<<"select name from sr_group;">>]) of
+	{selected, [<<"name">>], Rs} -> [G || [G] <- Rs];
+	_ -> []
+    end.
+
+groups_with_opts(Host) ->
+    case ejabberd_odbc:sql_query(Host,
+				 [<<"select name, opts from sr_group;">>])
+	of
+      {selected, [<<"name">>, <<"opts">>], Rs} ->
+	  [{G, mod_shared_roster:opts_to_binary(ejabberd_odbc:decode_term(Opts))}
+	   || [G, Opts] <- Rs];
+      _ -> []
+    end.
+
+create_group(Host, Group, Opts) ->
+    SGroup = ejabberd_odbc:escape(Group),
+    SOpts = ejabberd_odbc:encode_term(Opts),
+    F = fun () ->
+		odbc_queries:update_t(<<"sr_group">>,
+				      [<<"name">>, <<"opts">>], [SGroup, SOpts],
+				      [<<"name='">>, SGroup, <<"'">>])
+	end,
+    ejabberd_odbc:sql_transaction(Host, F).
+
+delete_group(Host, Group) ->
+    SGroup = ejabberd_odbc:escape(Group),
+    F = fun () ->
+		ejabberd_odbc:sql_query_t([<<"delete from sr_group where name='">>,
+					   SGroup, <<"';">>]),
+		ejabberd_odbc:sql_query_t([<<"delete from sr_user where grp='">>,
+					   SGroup, <<"';">>])
+	end,
+    case ejabberd_odbc:sql_transaction(Host, F) of
+        {atomic,{updated,_}} -> {atomic, ok};
+        Res -> Res
+    end.
+
+get_group_opts(Host, Group) ->
+    SGroup = ejabberd_odbc:escape(Group),
+    case catch ejabberd_odbc:sql_query(
+		 Host,
+		 [<<"select opts from sr_group where name='">>,
+		  SGroup, <<"';">>]) of
+	{selected, [<<"opts">>], [[SOpts]]} ->
+	    mod_shared_roster:opts_to_binary(ejabberd_odbc:decode_term(SOpts));
+	_ -> error
+    end.
+
+set_group_opts(Host, Group, Opts) ->
+    SGroup = ejabberd_odbc:escape(Group),
+    SOpts = ejabberd_odbc:encode_term(Opts),
+    F = fun () ->
+		odbc_queries:update_t(<<"sr_group">>,
+				      [<<"name">>, <<"opts">>], [SGroup, SOpts],
+				      [<<"name='">>, SGroup, <<"'">>])
+	end,
+    ejabberd_odbc:sql_transaction(Host, F).
+
+get_user_groups(US, Host) ->
+    SJID = make_jid_s(US),
+    case catch ejabberd_odbc:sql_query(
+		 Host,
+		 [<<"select grp from sr_user where jid='">>,
+		  SJID, <<"';">>]) of
+	{selected, [<<"grp">>], Rs} -> [G || [G] <- Rs];
+	_ -> []
+    end.
+
+get_group_explicit_users(Host, Group) ->
+    SGroup = ejabberd_odbc:escape(Group),
+    case catch ejabberd_odbc:sql_query(
+		 Host,
+		 [<<"select jid from sr_user where grp='">>,
+		  SGroup, <<"';">>]) of
+	{selected, [<<"jid">>], Rs} ->
+	    lists:map(
+	      fun([JID]) ->
+		      {U, S, _} = jid:tolower(jid:from_string(JID)),
+		      {U, S}
+	      end, Rs);
+	_ ->
+	    []
+    end.
+
+get_user_displayed_groups(LUser, LServer, GroupsOpts) ->
+    SJID = make_jid_s(LUser, LServer),
+    case catch ejabberd_odbc:sql_query(
+		 LServer,
+		 [<<"select grp from sr_user where jid='">>,
+		  SJID, <<"';">>]) of
+	{selected, [<<"grp">>], Rs} ->
+	    [{Group, proplists:get_value(Group, GroupsOpts, [])}
+	     || [Group] <- Rs];
+	_ -> []
+    end.
+
+is_user_in_group(US, Group, Host) ->
+    SJID = make_jid_s(US),
+    SGroup = ejabberd_odbc:escape(Group),
+    case catch ejabberd_odbc:sql_query(Host,
+				       [<<"select * from sr_user where jid='">>,
+					SJID, <<"' and grp='">>, SGroup,
+					<<"';">>]) of
+	{selected, _, []} -> false;
+	_ -> true
+    end.
+
+add_user_to_group(Host, US, Group) ->
+    SJID = make_jid_s(US),
+    SGroup = ejabberd_odbc:escape(Group),
+    F = fun () ->
+		odbc_queries:update_t(<<"sr_user">>,
+				      [<<"jid">>, <<"grp">>], [SJID, SGroup],
+				      [<<"jid='">>, SJID, <<"' and grp='">>,
+				       SGroup, <<"'">>])
+	end,
+    ejabberd_odbc:sql_transaction(Host, F).
+
+remove_user_from_group(Host, US, Group) ->
+    SJID = make_jid_s(US),
+    SGroup = ejabberd_odbc:escape(Group),
+    F = fun () ->
+		ejabberd_odbc:sql_query_t([<<"delete from sr_user where jid='">>,
+					   SJID, <<"' and grp='">>, SGroup,
+					   <<"';">>]),
+		ok
+	end,
+    ejabberd_odbc:sql_transaction(Host, F).
+
+export(_Server) ->
+    [{sr_group,
+      fun(Host, #sr_group{group_host = {Group, LServer}, opts = Opts})
+            when LServer == Host ->
+              SGroup = ejabberd_odbc:escape(Group),
+              SOpts = ejabberd_odbc:encode_term(Opts),
+              [[<<"delete from sr_group where name='">>, Group, <<"';">>],
+               [<<"insert into sr_group(name, opts) values ('">>,
+                SGroup, <<"', '">>, SOpts, <<"');">>]];
+         (_Host, _R) ->
+              []
+      end},
+     {sr_user,
+      fun(Host, #sr_user{us = {U, S}, group_host = {Group, LServer}})
+            when LServer == Host ->
+              SGroup = ejabberd_odbc:escape(Group),
+              SJID = ejabberd_odbc:escape(
+                       jid:to_string(
+                         jid:tolower(
+                           jid:make(U, S, <<"">>)))),
+              [[<<"delete from sr_user where jid='">>, SJID,
+                <<"'and grp='">>, Group, <<"';">>],
+               [<<"insert into sr_user(jid, grp) values ('">>,
+                SJID, <<"', '">>, SGroup, <<"');">>]];
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select name, opts from sr_group;">>,
+      fun([Group, SOpts]) ->
+              #sr_group{group_host = {Group, LServer},
+                        opts = ejabberd_odbc:decode_term(SOpts)}
+      end},
+     {<<"select jid, grp from sr_user;">>,
+      fun([SJID, Group]) ->
+              #jid{luser = U, lserver = S} = jid:from_string(SJID),
+              #sr_user{us = {U, S}, group_host = {Group, LServer}}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+make_jid_s(U, S) ->
+    ejabberd_odbc:escape(jid:to_string(jid:tolower(jid:make(U, S, <<"">>)))).
+
+make_jid_s({U, S}) -> make_jid_s(U, S).
diff --git a/src/mod_vcard.erl b/src/mod_vcard.erl
index 4d7c80d5..e5f5d9e3 100644
--- a/src/mod_vcard.erl
+++ b/src/mod_vcard.erl
@@ -25,8 +25,6 @@
 
 -module(mod_vcard).
 
--compile([{parse_transform, ejabberd_sql_pt}]).
-
 -author('alexey@process-one.net').
 
 -protocol({xep, 54, '1.2'}).
@@ -35,54 +33,31 @@
 -behaviour(gen_mod).
 
 -export([start/2, init/3, stop/1, get_sm_features/5,
-	 process_local_iq/3, process_sm_iq/3, reindex_vcards/0,
+	 process_local_iq/3, process_sm_iq/3, string2lower/1,
 	 remove_user/2, export/1, import/1, import/3,
-	 mod_opt_type/1, set_vcard/3]).
+	 mod_opt_type/1, set_vcard/3, make_vcard_search/4]).
 
 -include("ejabberd.hrl").
 -include("logger.hrl").
--include("ejabberd_sql_pt.hrl").
-
 -include("jlib.hrl").
+-include("mod_vcard.hrl").
 
 -define(JUD_MATCHES, 30).
 
--record(vcard_search,
-	{us, user, luser, fn, lfn, family, lfamily, given,
-	 lgiven, middle, lmiddle, nickname, lnickname, bday,
-	 lbday, ctry, lctry, locality, llocality, email, lemail,
-	 orgname, lorgname, orgunit, lorgunit}).
-
--record(vcard, {us = {<<"">>, <<"">>} :: {binary(), binary()} | binary(),
-                vcard = #xmlel{} :: xmlel()}).
-
 -define(PROCNAME, ejabberd_mod_vcard).
 
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #vcard{} | #vcard_search{}) -> ok | pass.
+-callback get_vcard(binary(), binary()) -> [xmlel()] | error.
+-callback set_vcard(binary(), binary(),
+		    xmlel(), #vcard_search{}) -> {atomic, any()}.
+-callback search(binary(), [{binary(), [binary()]}], boolean(),
+		 infinity | pos_integer()) -> [binary()].
+-callback remove_user(binary(), binary()) -> {atomic, any()}.
+
 start(Host, Opts) ->
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(vcard,
-			      [{disc_only_copies, [node()]},
-			       {attributes, record_info(fields, vcard)}]),
-	  mnesia:create_table(vcard_search,
-			      [{disc_copies, [node()]},
-			       {attributes,
-				record_info(fields, vcard_search)}]),
-	  update_tables(),
-	  mnesia:add_table_index(vcard_search, luser),
-	  mnesia:add_table_index(vcard_search, lfn),
-	  mnesia:add_table_index(vcard_search, lfamily),
-	  mnesia:add_table_index(vcard_search, lgiven),
-	  mnesia:add_table_index(vcard_search, lmiddle),
-	  mnesia:add_table_index(vcard_search, lnickname),
-	  mnesia:add_table_index(vcard_search, lbday),
-	  mnesia:add_table_index(vcard_search, lctry),
-	  mnesia:add_table_index(vcard_search, llocality),
-	  mnesia:add_table_index(vcard_search, lemail),
-	  mnesia:add_table_index(vcard_search, lorgname),
-	  mnesia:add_table_index(vcard_search, lorgunit);
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     ejabberd_hooks:add(remove_user, Host, ?MODULE,
 		       remove_user, 50),
     IQDisc = gen_mod:get_opt(iqdisc, Opts, fun gen_iq_handler:check_type/1,
@@ -206,38 +181,10 @@ process_sm_iq(From, To,
     end.
 
 get_vcard(LUser, LServer) ->
-    get_vcard(LUser, LServer,
-	      gen_mod:db_type(LServer, ?MODULE)).
-
-get_vcard(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () -> mnesia:read({vcard, US}) end,
-    case mnesia:transaction(F) of
-      {atomic, Rs} ->
-	  lists:map(fun (R) -> R#vcard.vcard end, Rs);
-      {aborted, _Reason} -> error
-    end;
-get_vcard(LUser, LServer, odbc) ->
-    case catch odbc_queries:get_vcard(LServer, LUser) of
-      {selected, [{SVCARD}]} ->
-	  case fxml_stream:parse_element(SVCARD) of
-	    {error, _Reason} -> error;
-	    VCARD -> [VCARD]
-	  end;
-      {selected, []} -> [];
-      _ -> error
-    end;
-get_vcard(LUser, LServer, riak) ->
-    case ejabberd_riak:get(vcard, vcard_schema(), {LUser, LServer}) of
-        {ok, R} ->
-            [R#vcard.vcard];
-        {error, notfound} ->
-            [];
-        _ ->
-            error
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_vcard(LUser, LServer).
 
-set_vcard(User, LServer, VCARD) ->
+make_vcard_search(User, LUser, LServer, VCARD) ->
     FN = fxml:get_path_s(VCARD, [{elem, <<"FN">>}, cdata]),
     Family = fxml:get_path_s(VCARD,
 			    [{elem, <<"N">>}, {elem, <<"FAMILY">>}, cdata]),
@@ -266,7 +213,6 @@ set_vcard(User, LServer, VCARD) ->
 	      <<"">> -> EMail2;
 	      _ -> EMail1
 	    end,
-    LUser = jid:nodeprep(User),
     LFN = string2lower(FN),
     LFamily = string2lower(Family),
     LGiven = string2lower(Given),
@@ -278,80 +224,42 @@ set_vcard(User, LServer, VCARD) ->
     LEMail = string2lower(EMail),
     LOrgName = string2lower(OrgName),
     LOrgUnit = string2lower(OrgUnit),
-    if (LUser == error) ->
-	   {error, badarg};
-       true ->
-	   case gen_mod:db_type(LServer, ?MODULE) of
-	     mnesia ->
-		 US = {LUser, LServer},
-		 F = fun () ->
-			     mnesia:write(#vcard{us = US, vcard = VCARD}),
-			     mnesia:write(#vcard_search{us = US,
-							user = {User, LServer},
-							luser = LUser, fn = FN,
-							lfn = LFN,
-							family = Family,
-							lfamily = LFamily,
-							given = Given,
-							lgiven = LGiven,
-							middle = Middle,
-							lmiddle = LMiddle,
-							nickname = Nickname,
-							lnickname = LNickname,
-							bday = BDay,
-							lbday = LBDay,
-							ctry = CTRY,
-							lctry = LCTRY,
-							locality = Locality,
-							llocality = LLocality,
-							email = EMail,
-							lemail = LEMail,
-							orgname = OrgName,
-							lorgname = LOrgName,
-							orgunit = OrgUnit,
-							lorgunit = LOrgUnit})
-		     end,
-		 mnesia:transaction(F);
-             riak ->
-                 US = {LUser, LServer},
-                 ejabberd_riak:put(#vcard{us = US, vcard = VCARD},
-				   vcard_schema(),
-                                   [{'2i', [{<<"user">>, User},
-                                            {<<"luser">>, LUser},
-                                            {<<"fn">>, FN},
-                                            {<<"lfn">>, LFN},
-                                            {<<"family">>, Family},
-                                            {<<"lfamily">>, LFamily},
-                                            {<<"given">>, Given},
-                                            {<<"lgiven">>, LGiven},
-                                            {<<"middle">>, Middle},
-                                            {<<"lmiddle">>, LMiddle},
-                                            {<<"nickname">>, Nickname},
-                                            {<<"lnickname">>, LNickname},
-                                            {<<"bday">>, BDay},
-                                            {<<"lbday">>, LBDay},
-                                            {<<"ctry">>, CTRY},
-                                            {<<"lctry">>, LCTRY},
-                                            {<<"locality">>, Locality},
-                                            {<<"llocality">>, LLocality},
-                                            {<<"email">>, EMail},
-                                            {<<"lemail">>, LEMail},
-                                            {<<"orgname">>, OrgName},
-                                            {<<"lorgname">>, LOrgName},
-                                            {<<"orgunit">>, OrgUnit},
-                                            {<<"lorgunit">>, LOrgUnit}]}]);
-	     odbc ->
-		 SVCARD = fxml:element_to_binary(VCARD),
-		 odbc_queries:set_vcard(LServer, LUser, BDay, CTRY,
-					EMail, FN, Family, Given, LBDay,
-					LCTRY, LEMail, LFN, LFamily,
-					LGiven, LLocality, LMiddle,
-					LNickname, LOrgName, LOrgUnit,
-					Locality, Middle, Nickname, OrgName,
-					OrgUnit, SVCARD, User)
-	   end,
-	   ejabberd_hooks:run(vcard_set, LServer,
-			      [LUser, LServer, VCARD])
+    US = {LUser, LServer},
+    #vcard_search{us = US,
+		  user = {User, LServer},
+		  luser = LUser, fn = FN,
+		  lfn = LFN,
+		  family = Family,
+		  lfamily = LFamily,
+		  given = Given,
+		  lgiven = LGiven,
+		  middle = Middle,
+		  lmiddle = LMiddle,
+		  nickname = Nickname,
+		  lnickname = LNickname,
+		  bday = BDay,
+		  lbday = LBDay,
+		  ctry = CTRY,
+		  lctry = LCTRY,
+		  locality = Locality,
+		  llocality = LLocality,
+		  email = EMail,
+		  lemail = LEMail,
+		  orgname = OrgName,
+		  lorgname = LOrgName,
+		  orgunit = OrgUnit,
+		  lorgunit = LOrgUnit}.
+
+set_vcard(User, LServer, VCARD) ->
+    case jid:nodeprep(User) of
+	error ->
+	    {error, badarg};
+	LUser ->
+	    VCardSearch = make_vcard_search(User, LUser, LServer, VCARD),
+	    Mod = gen_mod:db_mod(LServer, ?MODULE),
+	    Mod:set_vcard(LUser, LServer, VCARD, VCardSearch),
+	    ejabberd_hooks:run(vcard_set, LServer,
+			       [LUser, LServer, VCARD])
     end.
 
 string2lower(String) ->
@@ -655,500 +563,36 @@ record_to_item(_LServer, #vcard_search{} = R) ->
 		?FIELD(<<"orgunit">>, (R#vcard_search.orgunit))]}.
 
 search(LServer, Data) ->
-    DBType = gen_mod:db_type(LServer, ?MODULE),
-    MatchSpec = make_matchspec(LServer, Data, DBType),
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
     AllowReturnAll = gen_mod:get_module_opt(LServer, ?MODULE, allow_return_all,
                                             fun(B) when is_boolean(B) -> B end,
                                             false),
-    search(LServer, MatchSpec, AllowReturnAll, DBType).
-
-search(LServer, MatchSpec, AllowReturnAll, mnesia) ->
-    if (MatchSpec == #vcard_search{_ = '_'}) and
-	 not AllowReturnAll ->
-	   [];
-       true ->
-	   case catch mnesia:dirty_select(vcard_search,
-					  [{MatchSpec, [], ['$_']}])
-	       of
-	     {'EXIT', Reason} -> ?ERROR_MSG("~p", [Reason]), [];
-	     Rs ->
-		 case gen_mod:get_module_opt(LServer, ?MODULE, matches,
-                                             fun(infinity) -> infinity;
-                                                (I) when is_integer(I),
-                                                         I>0 ->
-                                                     I
-                                             end, ?JUD_MATCHES) of
-                     infinity ->
-                         Rs;
-                     Val ->
-                         lists:sublist(Rs, Val)
-                 end
-	   end
-    end;
-search(LServer, MatchSpec, AllowReturnAll, odbc) ->
-    if (MatchSpec == <<"">>) and not AllowReturnAll -> [];
-       true ->
-	   Limit = case gen_mod:get_module_opt(LServer, ?MODULE, matches,
-                                               fun(infinity) -> infinity;
-                                                  (I) when is_integer(I),
-                                                           I>0 ->
-                                                       I
-                                               end, ?JUD_MATCHES) of
-                       infinity ->
-                           <<"">>;
-                       Val ->
-                           [<<" LIMIT ">>,
-                            jlib:integer_to_binary(Val)]
-                   end,
-	   case catch ejabberd_odbc:sql_query(LServer,
-					      [<<"select username, fn, family, given, "
-						 "middle,        nickname, bday, ctry, "
-						 "locality,        email, orgname, orgunit "
-						 "from vcard_search ">>,
-					       MatchSpec, Limit, <<";">>])
-	       of
-	     {selected,
-	      [<<"username">>, <<"fn">>, <<"family">>, <<"given">>,
-	       <<"middle">>, <<"nickname">>, <<"bday">>, <<"ctry">>,
-	       <<"locality">>, <<"email">>, <<"orgname">>,
-	       <<"orgunit">>],
-	      Rs}
-		 when is_list(Rs) ->
-		 Rs;
-	     Error -> ?ERROR_MSG("~p", [Error]), []
-	   end
-    end;
-search(_LServer, _MatchSpec, _AllowReturnAll, riak) ->
-    [].
-
-make_matchspec(LServer, Data, mnesia) ->
-    GlobMatch = #vcard_search{_ = '_'},
-    Match = filter_fields(Data, GlobMatch, LServer, mnesia),
-    Match;
-make_matchspec(LServer, Data, odbc) ->
-    filter_fields(Data, <<"">>, LServer, odbc);
-make_matchspec(_LServer, _Data, riak) ->
-    [].
-
-filter_fields([], Match, _LServer, mnesia) -> Match;
-filter_fields([], Match, _LServer, odbc) ->
-    case Match of
-      <<"">> -> <<"">>;
-      _ -> [<<" where ">>, Match]
-    end;
-filter_fields([{SVar, [Val]} | Ds], Match, LServer,
-	      mnesia)
-    when is_binary(Val) and (Val /= <<"">>) ->
-    LVal = string2lower(Val),
-    NewMatch = case SVar of
-		 <<"user">> ->
-		     case gen_mod:get_module_opt(LServer, ?MODULE,
-                                                 search_all_hosts,
-                                                 fun(B) when is_boolean(B) ->
-                                                         B
-                                                 end, true)
-			 of
-		       true -> Match#vcard_search{luser = make_val(LVal)};
-		       false ->
-			   Host = find_my_host(LServer),
-			   Match#vcard_search{us = {make_val(LVal), Host}}
-		     end;
-		 <<"fn">> -> Match#vcard_search{lfn = make_val(LVal)};
-		 <<"last">> ->
-		     Match#vcard_search{lfamily = make_val(LVal)};
-		 <<"first">> ->
-		     Match#vcard_search{lgiven = make_val(LVal)};
-		 <<"middle">> ->
-		     Match#vcard_search{lmiddle = make_val(LVal)};
-		 <<"nick">> ->
-		     Match#vcard_search{lnickname = make_val(LVal)};
-		 <<"bday">> ->
-		     Match#vcard_search{lbday = make_val(LVal)};
-		 <<"ctry">> ->
-		     Match#vcard_search{lctry = make_val(LVal)};
-		 <<"locality">> ->
-		     Match#vcard_search{llocality = make_val(LVal)};
-		 <<"email">> ->
-		     Match#vcard_search{lemail = make_val(LVal)};
-		 <<"orgname">> ->
-		     Match#vcard_search{lorgname = make_val(LVal)};
-		 <<"orgunit">> ->
-		     Match#vcard_search{lorgunit = make_val(LVal)};
-		 _ -> Match
-	       end,
-    filter_fields(Ds, NewMatch, LServer, mnesia);
-filter_fields([{SVar, [Val]} | Ds], Match, LServer,
-	      odbc)
-    when is_binary(Val) and (Val /= <<"">>) ->
-    LVal = string2lower(Val),
-    NewMatch = case SVar of
-		 <<"user">> -> make_val(Match, <<"lusername">>, LVal);
-		 <<"fn">> -> make_val(Match, <<"lfn">>, LVal);
-		 <<"last">> -> make_val(Match, <<"lfamily">>, LVal);
-		 <<"first">> -> make_val(Match, <<"lgiven">>, LVal);
-		 <<"middle">> -> make_val(Match, <<"lmiddle">>, LVal);
-		 <<"nick">> -> make_val(Match, <<"lnickname">>, LVal);
-		 <<"bday">> -> make_val(Match, <<"lbday">>, LVal);
-		 <<"ctry">> -> make_val(Match, <<"lctry">>, LVal);
-		 <<"locality">> ->
-		     make_val(Match, <<"llocality">>, LVal);
-		 <<"email">> -> make_val(Match, <<"lemail">>, LVal);
-		 <<"orgname">> -> make_val(Match, <<"lorgname">>, LVal);
-		 <<"orgunit">> -> make_val(Match, <<"lorgunit">>, LVal);
-		 _ -> Match
-	       end,
-    filter_fields(Ds, NewMatch, LServer, odbc);
-filter_fields([_ | Ds], Match, LServer, DBType) ->
-    filter_fields(Ds, Match, LServer, DBType).
-
-make_val(Match, Field, Val) ->
-    Condition = case str:suffix(<<"*">>, Val) of
-		  true ->
-		      Val1 = str:substr(Val, 1, byte_size(Val) - 1),
-		      SVal = <<(ejabberd_odbc:escape_like(Val1))/binary,
-			       "%">>,
-		      [Field, <<" LIKE '">>, SVal, <<"'">>];
-		  _ ->
-		      SVal = ejabberd_odbc:escape(Val),
-		      [Field, <<" = '">>, SVal, <<"'">>]
-		end,
-    case Match of
-      <<"">> -> Condition;
-      _ -> [Match, <<" and ">>, Condition]
-    end.
-
-make_val(Val) ->
-    case str:suffix(<<"*">>, Val) of
-      true -> [str:substr(Val, 1, byte_size(Val) - 1)] ++ '_';
-      _ -> Val
-    end.
-
-find_my_host(LServer) ->
-    Parts = str:tokens(LServer, <<".">>),
-    find_my_host(Parts, ?MYHOSTS).
-
-find_my_host([], _Hosts) -> ?MYNAME;
-find_my_host([_ | Tail] = Parts, Hosts) ->
-    Domain = parts_to_string(Parts),
-    case lists:member(Domain, Hosts) of
-      true -> Domain;
-      false -> find_my_host(Tail, Hosts)
-    end.
-
-parts_to_string(Parts) ->
-    str:strip(list_to_binary(
-                lists:map(fun (S) -> <<S/binary, $.>> end, Parts)),
-              right, $.).
+    MaxMatch = gen_mod:get_module_opt(LServer, ?MODULE, matches,
+				      fun(infinity) -> infinity;
+					 (I) when is_integer(I),
+						  I>0 ->
+					      I
+				      end, ?JUD_MATCHES),
+    Mod:search(LServer, Data, AllowReturnAll, MaxMatch).
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-set_vcard_t(R, _) ->
-    US = R#vcard.us,
-    User = US,
-    VCARD = R#vcard.vcard,
-    FN = fxml:get_path_s(VCARD, [{elem, <<"FN">>}, cdata]),
-    Family = fxml:get_path_s(VCARD,
-			    [{elem, <<"N">>}, {elem, <<"FAMILY">>}, cdata]),
-    Given = fxml:get_path_s(VCARD,
-			   [{elem, <<"N">>}, {elem, <<"GIVEN">>}, cdata]),
-    Middle = fxml:get_path_s(VCARD,
-			    [{elem, <<"N">>}, {elem, <<"MIDDLE">>}, cdata]),
-    Nickname = fxml:get_path_s(VCARD,
-			      [{elem, <<"NICKNAME">>}, cdata]),
-    BDay = fxml:get_path_s(VCARD,
-			  [{elem, <<"BDAY">>}, cdata]),
-    CTRY = fxml:get_path_s(VCARD,
-			  [{elem, <<"ADR">>}, {elem, <<"CTRY">>}, cdata]),
-    Locality = fxml:get_path_s(VCARD,
-			      [{elem, <<"ADR">>}, {elem, <<"LOCALITY">>},
-			       cdata]),
-    EMail = fxml:get_path_s(VCARD,
-			   [{elem, <<"EMAIL">>}, cdata]),
-    OrgName = fxml:get_path_s(VCARD,
-			     [{elem, <<"ORG">>}, {elem, <<"ORGNAME">>}, cdata]),
-    OrgUnit = fxml:get_path_s(VCARD,
-			     [{elem, <<"ORG">>}, {elem, <<"ORGUNIT">>}, cdata]),
-    {LUser, _LServer} = US,
-    LFN = string2lower(FN),
-    LFamily = string2lower(Family),
-    LGiven = string2lower(Given),
-    LMiddle = string2lower(Middle),
-    LNickname = string2lower(Nickname),
-    LBDay = string2lower(BDay),
-    LCTRY = string2lower(CTRY),
-    LLocality = string2lower(Locality),
-    LEMail = string2lower(EMail),
-    LOrgName = string2lower(OrgName),
-    LOrgUnit = string2lower(OrgUnit),
-    mnesia:write(#vcard_search{us = US, user = User,
-                               luser = LUser, fn = FN, lfn = LFN,
-                               family = Family, lfamily = LFamily,
-                               given = Given, lgiven = LGiven,
-                               middle = Middle, lmiddle = LMiddle,
-                               nickname = Nickname,
-                               lnickname = LNickname, bday = BDay,
-                               lbday = LBDay, ctry = CTRY, lctry = LCTRY,
-                               locality = Locality,
-                               llocality = LLocality, email = EMail,
-                               lemail = LEMail, orgname = OrgName,
-                               lorgname = LOrgName, orgunit = OrgUnit,
-                               lorgunit = LOrgUnit}).
-
-reindex_vcards() ->
-    F = fun () -> mnesia:foldl(fun set_vcard_t/2, [], vcard)
-	end,
-    mnesia:transaction(F).
-
 remove_user(User, Server) ->
     LUser = jid:nodeprep(User),
     LServer = jid:nameprep(Server),
-    remove_user(LUser, LServer,
-		gen_mod:db_type(LServer, ?MODULE)).
-
-remove_user(LUser, LServer, mnesia) ->
-    US = {LUser, LServer},
-    F = fun () ->
-		mnesia:delete({vcard, US}),
-		mnesia:delete({vcard_search, US})
-	end,
-    mnesia:transaction(F);
-remove_user(LUser, LServer, odbc) ->
-    ejabberd_odbc:sql_transaction(
-      LServer,
-      fun() ->
-              ejabberd_odbc:sql_query_t(
-                ?SQL("delete from vcard where username=%(LUser)s")),
-              ejabberd_odbc:sql_query_t(
-                ?SQL("delete from vcard_search where lusername=%(LUser)s"))
-      end);
-remove_user(LUser, LServer, riak) ->
-    {atomic, ejabberd_riak:delete(vcard, {LUser, LServer})}.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_user(LUser, LServer).
 
-update_tables() ->
-    update_vcard_table(),
-    update_vcard_search_table().
-
-update_vcard_table() ->
-    Fields = record_info(fields, vcard),
-    case mnesia:table_info(vcard, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            vcard, Fields, set,
-            fun(#vcard{us = {U, _}}) -> U end,
-            fun(#vcard{us = {U, S}, vcard = El} = R) ->
-                    R#vcard{us = {iolist_to_binary(U),
-                                  iolist_to_binary(S)},
-                            vcard = fxml:to_xmlel(El)}
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating vcard table", []),
-	  mnesia:transform_table(vcard, ignore, Fields)
-    end.
-
-update_vcard_search_table() ->
-    Fields = record_info(fields, vcard_search),
-    case mnesia:table_info(vcard_search, attributes) of
-      Fields ->
-          ejabberd_config:convert_table_to_binary(
-            vcard_search, Fields, set,
-            fun(#vcard_search{us = {U, _}}) -> U end,
-            fun(#vcard_search{} = VS) ->
-                    [vcard_search | L] = tuple_to_list(VS),
-                    NewL = lists:map(
-                             fun({U, S}) ->
-                                     {iolist_to_binary(U),
-                                      iolist_to_binary(S)};
-                                (Str) ->
-                                     iolist_to_binary(Str)
-                             end, L),
-                    list_to_tuple([vcard_search | NewL])
-            end);
-      _ ->
-	  ?INFO_MSG("Recreating vcard_search table", []),
-	  mnesia:transform_table(vcard_search, ignore, Fields)
-    end.
-
-vcard_schema() ->
-    {record_info(fields, vcard), #vcard{}}.
-
-export(_Server) ->   
-    [{vcard,
-      fun(Host, #vcard{us = {LUser, LServer}, vcard = VCARD})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              SVCARD =
-                  ejabberd_odbc:escape(fxml:element_to_binary(VCARD)),
-              [[<<"delete from vcard where username='">>, Username, <<"';">>],
-               [<<"insert into vcard(username, vcard) values ('">>,
-                Username, <<"', '">>, SVCARD, <<"');">>]];
-         (_Host, _R) ->
-              []
-      end},
-     {vcard_search,
-      fun(Host, #vcard_search{user = {User, LServer}, luser = LUser,
-                              fn = FN, lfn = LFN, family = Family,
-                              lfamily = LFamily, given = Given,
-                              lgiven = LGiven, middle = Middle,
-                              lmiddle = LMiddle, nickname = Nickname,
-                              lnickname = LNickname, bday = BDay,
-                              lbday = LBDay, ctry = CTRY, lctry = LCTRY,
-                              locality = Locality, llocality = LLocality,
-                              email = EMail, lemail = LEMail,
-                              orgname = OrgName, lorgname = LOrgName,
-                              orgunit = OrgUnit, lorgunit = LOrgUnit})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(User),
-              LUsername = ejabberd_odbc:escape(LUser),
-              SFN = ejabberd_odbc:escape(FN),
-              SLFN = ejabberd_odbc:escape(LFN),
-              SFamily = ejabberd_odbc:escape(Family),
-              SLFamily = ejabberd_odbc:escape(LFamily),
-              SGiven = ejabberd_odbc:escape(Given),
-              SLGiven = ejabberd_odbc:escape(LGiven),
-              SMiddle = ejabberd_odbc:escape(Middle),
-              SLMiddle = ejabberd_odbc:escape(LMiddle),
-              SNickname = ejabberd_odbc:escape(Nickname),
-              SLNickname = ejabberd_odbc:escape(LNickname),
-              SBDay = ejabberd_odbc:escape(BDay),
-              SLBDay = ejabberd_odbc:escape(LBDay),
-              SCTRY = ejabberd_odbc:escape(CTRY),
-              SLCTRY = ejabberd_odbc:escape(LCTRY),
-              SLocality = ejabberd_odbc:escape(Locality),
-              SLLocality = ejabberd_odbc:escape(LLocality),
-              SEMail = ejabberd_odbc:escape(EMail),
-              SLEMail = ejabberd_odbc:escape(LEMail),
-              SOrgName = ejabberd_odbc:escape(OrgName),
-              SLOrgName = ejabberd_odbc:escape(LOrgName),
-              SOrgUnit = ejabberd_odbc:escape(OrgUnit),
-              SLOrgUnit = ejabberd_odbc:escape(LOrgUnit),
-              [[<<"delete from vcard_search where lusername='">>,
-                LUsername, <<"';">>],
-               [<<"insert into vcard_search(        username, "
-                  "lusername, fn, lfn, family, lfamily, "
-                  "       given, lgiven, middle, lmiddle, "
-                  "nickname, lnickname,        bday, lbday, "
-                  "ctry, lctry, locality, llocality,   "
-                  "     email, lemail, orgname, lorgname, "
-                  "orgunit, lorgunit)values (">>,
-                <<"        '">>, Username, <<"', '">>, LUsername,
-                <<"',        '">>, SFN, <<"', '">>, SLFN,
-                <<"',        '">>, SFamily, <<"', '">>, SLFamily,
-                <<"',        '">>, SGiven, <<"', '">>, SLGiven,
-                <<"',        '">>, SMiddle, <<"', '">>, SLMiddle,
-                <<"',        '">>, SNickname, <<"', '">>, SLNickname,
-                <<"',        '">>, SBDay, <<"', '">>, SLBDay,
-                <<"',        '">>, SCTRY, <<"', '">>, SLCTRY,
-                <<"',        '">>, SLocality, <<"', '">>, SLLocality,
-                <<"',        '">>, SEMail, <<"', '">>, SLEMail,
-                <<"',        '">>, SOrgName, <<"', '">>, SLOrgName,
-                <<"',        '">>, SOrgUnit, <<"', '">>, SLOrgUnit,
-                <<"');">>]];
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select username, vcard from vcard;">>,
-      fun([LUser, SVCard]) ->
-              #xmlel{} = VCARD = fxml_stream:parse_element(SVCard),
-              #vcard{us = {LUser, LServer}, vcard = VCARD}
-      end},
-     {<<"select username, lusername, fn, lfn, family, lfamily, "
-        "given, lgiven, middle, lmiddle, nickname, lnickname, "
-        "bday, lbday, ctry, lctry, locality, llocality, email, "
-        "lemail, orgname, lorgname, orgunit, lorgunit from vcard_search;">>,
-      fun([User, LUser, FN, LFN,
-           Family, LFamily, Given, LGiven,
-           Middle, LMiddle, Nickname, LNickname,
-           BDay, LBDay, CTRY, LCTRY, Locality, LLocality,
-           EMail, LEMail, OrgName, LOrgName, OrgUnit, LOrgUnit]) ->
-              #vcard_search{us = {LUser, LServer},
-                            user = {User, LServer}, luser = LUser,
-                            fn = FN, lfn = LFN, family = Family,
-                            lfamily = LFamily, given = Given,
-                            lgiven = LGiven, middle = Middle,
-                            lmiddle = LMiddle, nickname = Nickname,
-                            lnickname = LNickname, bday = BDay,
-                            lbday = LBDay, ctry = CTRY, lctry = LCTRY,
-                            locality = Locality, llocality = LLocality,
-                            email = EMail, lemail = LEMail,
-                            orgname = OrgName, lorgname = LOrgName,
-                            orgunit = OrgUnit, lorgunit = LOrgUnit}
-      end}].
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
 
-import(_LServer, mnesia, #vcard{} = VCard) ->
-    mnesia:dirty_write(VCard);
-import(_LServer, mnesia, #vcard_search{} = S) ->
-    mnesia:dirty_write(S);
-import(_LServer, riak, #vcard{us = {LUser, _}, vcard = El} = VCard) ->
-    FN = fxml:get_path_s(El, [{elem, <<"FN">>}, cdata]),
-    Family = fxml:get_path_s(El,
-			    [{elem, <<"N">>}, {elem, <<"FAMILY">>}, cdata]),
-    Given = fxml:get_path_s(El,
-			   [{elem, <<"N">>}, {elem, <<"GIVEN">>}, cdata]),
-    Middle = fxml:get_path_s(El,
-			    [{elem, <<"N">>}, {elem, <<"MIDDLE">>}, cdata]),
-    Nickname = fxml:get_path_s(El,
-			      [{elem, <<"NICKNAME">>}, cdata]),
-    BDay = fxml:get_path_s(El,
-			  [{elem, <<"BDAY">>}, cdata]),
-    CTRY = fxml:get_path_s(El,
-			  [{elem, <<"ADR">>}, {elem, <<"CTRY">>}, cdata]),
-    Locality = fxml:get_path_s(El,
-			      [{elem, <<"ADR">>}, {elem, <<"LOCALITY">>},
-			       cdata]),
-    EMail1 = fxml:get_path_s(El,
-			    [{elem, <<"EMAIL">>}, {elem, <<"USERID">>}, cdata]),
-    EMail2 = fxml:get_path_s(El,
-			    [{elem, <<"EMAIL">>}, cdata]),
-    OrgName = fxml:get_path_s(El,
-			     [{elem, <<"ORG">>}, {elem, <<"ORGNAME">>}, cdata]),
-    OrgUnit = fxml:get_path_s(El,
-			     [{elem, <<"ORG">>}, {elem, <<"ORGUNIT">>}, cdata]),
-    EMail = case EMail1 of
-	      <<"">> -> EMail2;
-	      _ -> EMail1
-	    end,
-    LFN = string2lower(FN),
-    LFamily = string2lower(Family),
-    LGiven = string2lower(Given),
-    LMiddle = string2lower(Middle),
-    LNickname = string2lower(Nickname),
-    LBDay = string2lower(BDay),
-    LCTRY = string2lower(CTRY),
-    LLocality = string2lower(Locality),
-    LEMail = string2lower(EMail),
-    LOrgName = string2lower(OrgName),
-    LOrgUnit = string2lower(OrgUnit),
-    ejabberd_riak:put(VCard, vcard_schema(),
-                      [{'2i', [{<<"user">>, LUser},
-                               {<<"luser">>, LUser},
-                               {<<"fn">>, FN},
-                               {<<"lfn">>, LFN},
-                               {<<"family">>, Family},
-                               {<<"lfamily">>, LFamily},
-                               {<<"given">>, Given},
-                               {<<"lgiven">>, LGiven},
-                               {<<"middle">>, Middle},
-                               {<<"lmiddle">>, LMiddle},
-                               {<<"nickname">>, Nickname},
-                               {<<"lnickname">>, LNickname},
-                               {<<"bday">>, BDay},
-                               {<<"lbday">>, LBDay},
-                               {<<"ctry">>, CTRY},
-                               {<<"lctry">>, LCTRY},
-                               {<<"locality">>, Locality},
-                               {<<"llocality">>, LLocality},
-                               {<<"email">>, EMail},
-                               {<<"lemail">>, LEMail},
-                               {<<"orgname">>, OrgName},
-                               {<<"lorgname">>, LOrgName},
-                               {<<"orgunit">>, OrgUnit},
-                               {<<"lorgunit">>, LOrgUnit}]}]);
-import(_LServer, riak, #vcard_search{}) ->
-    ok;
-import(_, _, _) ->
-    pass.
+import(LServer, DBType, VCard) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, VCard).
 
 mod_opt_type(allow_return_all) ->
     fun (B) when is_boolean(B) -> B end;
diff --git a/src/mod_vcard_mnesia.erl b/src/mod_vcard_mnesia.erl
new file mode 100644
index 00000000..781a135c
--- /dev/null
+++ b/src/mod_vcard_mnesia.erl
@@ -0,0 +1,213 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_vcard_mnesia).
+
+-behaviour(mod_vcard).
+
+%% API
+-export([init/2, import/2, get_vcard/2, set_vcard/4, search/4, remove_user/2]).
+
+-include("ejabberd.hrl").
+-include("jlib.hrl").
+-include("mod_vcard.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(vcard,
+			[{disc_only_copies, [node()]},
+			 {attributes, record_info(fields, vcard)}]),
+    mnesia:create_table(vcard_search,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, vcard_search)}]),
+    update_tables(),
+    mnesia:add_table_index(vcard_search, luser),
+    mnesia:add_table_index(vcard_search, lfn),
+    mnesia:add_table_index(vcard_search, lfamily),
+    mnesia:add_table_index(vcard_search, lgiven),
+    mnesia:add_table_index(vcard_search, lmiddle),
+    mnesia:add_table_index(vcard_search, lnickname),
+    mnesia:add_table_index(vcard_search, lbday),
+    mnesia:add_table_index(vcard_search, lctry),
+    mnesia:add_table_index(vcard_search, llocality),
+    mnesia:add_table_index(vcard_search, lemail),
+    mnesia:add_table_index(vcard_search, lorgname),
+    mnesia:add_table_index(vcard_search, lorgunit).
+
+get_vcard(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () -> mnesia:read({vcard, US}) end,
+    case mnesia:transaction(F) of
+	{atomic, Rs} ->
+	    lists:map(fun (R) -> R#vcard.vcard end, Rs);
+	{aborted, _Reason} -> error
+    end.
+
+set_vcard(LUser, LServer, VCARD, VCardSearch) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		mnesia:write(#vcard{us = US, vcard = VCARD}),
+		mnesia:write(VCardSearch)
+	end,
+    mnesia:transaction(F).
+
+search(LServer, Data, AllowReturnAll, MaxMatch) ->
+    MatchSpec = make_matchspec(LServer, Data),
+    if (MatchSpec == #vcard_search{_ = '_'}) and
+       not AllowReturnAll ->
+	    [];
+       true ->
+	    case catch mnesia:dirty_select(vcard_search,
+					   [{MatchSpec, [], ['$_']}]) of
+		{'EXIT', Reason} ->
+		    ?ERROR_MSG("~p", [Reason]), [];
+		Rs ->
+		    case MaxMatch of
+			infinity ->
+			    Rs;
+			Val ->
+			    lists:sublist(Rs, Val)
+		    end
+	    end
+    end.
+
+remove_user(LUser, LServer) ->
+    US = {LUser, LServer},
+    F = fun () ->
+		mnesia:delete({vcard, US}),
+		mnesia:delete({vcard_search, US})
+	end,
+    mnesia:transaction(F).
+
+import(_LServer, #vcard{} = VCard) ->
+    mnesia:dirty_write(VCard);
+import(_LServer, #vcard_search{} = S) ->
+    mnesia:dirty_write(S).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_tables() ->
+    update_vcard_table(),
+    update_vcard_search_table().
+
+update_vcard_table() ->
+    Fields = record_info(fields, vcard),
+    case mnesia:table_info(vcard, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            vcard, Fields, set,
+            fun(#vcard{us = {U, _}}) -> U end,
+            fun(#vcard{us = {U, S}, vcard = El} = R) ->
+                    R#vcard{us = {iolist_to_binary(U),
+                                  iolist_to_binary(S)},
+                            vcard = fxml:to_xmlel(El)}
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating vcard table", []),
+	  mnesia:transform_table(vcard, ignore, Fields)
+    end.
+
+update_vcard_search_table() ->
+    Fields = record_info(fields, vcard_search),
+    case mnesia:table_info(vcard_search, attributes) of
+      Fields ->
+          ejabberd_config:convert_table_to_binary(
+            vcard_search, Fields, set,
+            fun(#vcard_search{us = {U, _}}) -> U end,
+            fun(#vcard_search{} = VS) ->
+                    [vcard_search | L] = tuple_to_list(VS),
+                    NewL = lists:map(
+                             fun({U, S}) ->
+                                     {iolist_to_binary(U),
+                                      iolist_to_binary(S)};
+                                (Str) ->
+                                     iolist_to_binary(Str)
+                             end, L),
+                    list_to_tuple([vcard_search | NewL])
+            end);
+      _ ->
+	  ?INFO_MSG("Recreating vcard_search table", []),
+	  mnesia:transform_table(vcard_search, ignore, Fields)
+    end.
+
+make_matchspec(LServer, Data) ->
+    GlobMatch = #vcard_search{_ = '_'},
+    Match = filter_fields(Data, GlobMatch, LServer),
+    Match.
+
+filter_fields([], Match, _LServer) ->
+    Match;
+filter_fields([{SVar, [Val]} | Ds], Match, LServer)
+  when is_binary(Val) and (Val /= <<"">>) ->
+    LVal = mod_vcard:string2lower(Val),
+    NewMatch = case SVar of
+		   <<"user">> ->
+		       case gen_mod:get_module_opt(LServer, ?MODULE,
+						   search_all_hosts,
+						   fun(B) when is_boolean(B) ->
+							   B
+						   end, true) of
+			   true -> Match#vcard_search{luser = make_val(LVal)};
+			   false ->
+			       Host = find_my_host(LServer),
+			       Match#vcard_search{us = {make_val(LVal), Host}}
+		       end;
+		   <<"fn">> -> Match#vcard_search{lfn = make_val(LVal)};
+		   <<"last">> ->
+		       Match#vcard_search{lfamily = make_val(LVal)};
+		   <<"first">> ->
+		       Match#vcard_search{lgiven = make_val(LVal)};
+		   <<"middle">> ->
+		       Match#vcard_search{lmiddle = make_val(LVal)};
+		   <<"nick">> ->
+		       Match#vcard_search{lnickname = make_val(LVal)};
+		   <<"bday">> ->
+		       Match#vcard_search{lbday = make_val(LVal)};
+		   <<"ctry">> ->
+		       Match#vcard_search{lctry = make_val(LVal)};
+		   <<"locality">> ->
+		       Match#vcard_search{llocality = make_val(LVal)};
+		   <<"email">> ->
+		       Match#vcard_search{lemail = make_val(LVal)};
+		   <<"orgname">> ->
+		       Match#vcard_search{lorgname = make_val(LVal)};
+		 <<"orgunit">> ->
+		       Match#vcard_search{lorgunit = make_val(LVal)};
+		   _ -> Match
+	       end,
+    filter_fields(Ds, NewMatch, LServer);
+filter_fields([_ | Ds], Match, LServer) ->
+    filter_fields(Ds, Match, LServer).
+
+make_val(Val) ->
+    case str:suffix(<<"*">>, Val) of
+      true -> [str:substr(Val, 1, byte_size(Val) - 1)] ++ '_';
+      _ -> Val
+    end.
+
+find_my_host(LServer) ->
+    Parts = str:tokens(LServer, <<".">>),
+    find_my_host(Parts, ?MYHOSTS).
+
+find_my_host([], _Hosts) -> ?MYNAME;
+find_my_host([_ | Tail] = Parts, Hosts) ->
+    Domain = parts_to_string(Parts),
+    case lists:member(Domain, Hosts) of
+      true -> Domain;
+      false -> find_my_host(Tail, Hosts)
+    end.
+
+parts_to_string(Parts) ->
+    str:strip(list_to_binary(
+                lists:map(fun (S) -> <<S/binary, $.>> end, Parts)),
+              right, $.).
diff --git a/src/mod_vcard_riak.erl b/src/mod_vcard_riak.erl
new file mode 100644
index 00000000..38634738
--- /dev/null
+++ b/src/mod_vcard_riak.erl
@@ -0,0 +1,151 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_vcard_riak).
+
+-behaviour(mod_vcard).
+
+%% API
+-export([init/2, get_vcard/2, set_vcard/4, search/4, remove_user/2,
+	 import/2]).
+
+-include("jlib.hrl").
+-include("mod_vcard.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+get_vcard(LUser, LServer) ->
+    case ejabberd_riak:get(vcard, vcard_schema(), {LUser, LServer}) of
+        {ok, R} ->
+            [R#vcard.vcard];
+        {error, notfound} ->
+            [];
+        _ ->
+            error
+    end.
+
+set_vcard(LUser, LServer, VCARD,
+	  #vcard_search{user = {User, _},
+			fn = FN,
+			lfn = LFN,
+			family = Family,
+			lfamily = LFamily,
+			given = Given,
+			lgiven = LGiven,
+			middle = Middle,
+			lmiddle = LMiddle,
+			nickname = Nickname,
+			lnickname = LNickname,
+			bday = BDay,
+			lbday = LBDay,
+			ctry = CTRY,
+			lctry = LCTRY,
+			locality = Locality,
+			llocality = LLocality,
+			email = EMail,
+			lemail = LEMail,
+			orgname = OrgName,
+			lorgname = LOrgName,
+			orgunit = OrgUnit,
+			lorgunit = LOrgUnit}) ->
+    US = {LUser, LServer},
+    {atomic,
+     ejabberd_riak:put(#vcard{us = US, vcard = VCARD},
+		       vcard_schema(),
+		       [{'2i', [{<<"user">>, User},
+				{<<"luser">>, LUser},
+				{<<"fn">>, FN},
+				{<<"lfn">>, LFN},
+				{<<"family">>, Family},
+				{<<"lfamily">>, LFamily},
+				{<<"given">>, Given},
+				{<<"lgiven">>, LGiven},
+				{<<"middle">>, Middle},
+				{<<"lmiddle">>, LMiddle},
+				{<<"nickname">>, Nickname},
+				{<<"lnickname">>, LNickname},
+				{<<"bday">>, BDay},
+				{<<"lbday">>, LBDay},
+				{<<"ctry">>, CTRY},
+				{<<"lctry">>, LCTRY},
+				{<<"locality">>, Locality},
+				{<<"llocality">>, LLocality},
+				{<<"email">>, EMail},
+				{<<"lemail">>, LEMail},
+				{<<"orgname">>, OrgName},
+				{<<"lorgname">>, LOrgName},
+				{<<"orgunit">>, OrgUnit},
+				{<<"lorgunit">>, LOrgUnit}]}])}.
+
+search(_LServer, _Data, _AllowReturnAll, _MaxMatch) ->
+    [].
+
+remove_user(LUser, LServer) ->
+    {atomic, ejabberd_riak:delete(vcard, {LUser, LServer})}.
+
+import(_LServer, #vcard{us = {LUser, LServer}, vcard = El} = VCard) ->
+    #vcard_search{fn = FN,
+		  lfn = LFN,
+		  family = Family,
+		  lfamily = LFamily,
+		  given = Given,
+		  lgiven = LGiven,
+		  middle = Middle,
+		  lmiddle = LMiddle,
+		  nickname = Nickname,
+		  lnickname = LNickname,
+		  bday = BDay,
+		  lbday = LBDay,
+		  ctry = CTRY,
+		  lctry = LCTRY,
+		  locality = Locality,
+		  llocality = LLocality,
+		  email = EMail,
+		  lemail = LEMail,
+		  orgname = OrgName,
+		  lorgname = LOrgName,
+		  orgunit = OrgUnit,
+		  lorgunit = LOrgUnit} =
+	mod_vcard:make_vcard_search(LUser, LUser, LServer, El),
+    ejabberd_riak:put(VCard, vcard_schema(),
+                      [{'2i', [{<<"user">>, LUser},
+                               {<<"luser">>, LUser},
+                               {<<"fn">>, FN},
+                               {<<"lfn">>, LFN},
+                               {<<"family">>, Family},
+                               {<<"lfamily">>, LFamily},
+                               {<<"given">>, Given},
+                               {<<"lgiven">>, LGiven},
+                               {<<"middle">>, Middle},
+                               {<<"lmiddle">>, LMiddle},
+                               {<<"nickname">>, Nickname},
+                               {<<"lnickname">>, LNickname},
+                               {<<"bday">>, BDay},
+                               {<<"lbday">>, LBDay},
+                               {<<"ctry">>, CTRY},
+                               {<<"lctry">>, LCTRY},
+                               {<<"locality">>, Locality},
+                               {<<"llocality">>, LLocality},
+                               {<<"email">>, EMail},
+                               {<<"lemail">>, LEMail},
+                               {<<"orgname">>, OrgName},
+                               {<<"lorgname">>, LOrgName},
+                               {<<"orgunit">>, OrgUnit},
+                               {<<"lorgunit">>, LOrgUnit}]}]);
+import(_LServer, #vcard_search{}) ->
+    ok.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+vcard_schema() ->
+    {record_info(fields, vcard), #vcard{}}.
diff --git a/src/mod_vcard_sql.erl b/src/mod_vcard_sql.erl
new file mode 100644
index 00000000..fff39091
--- /dev/null
+++ b/src/mod_vcard_sql.erl
@@ -0,0 +1,268 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_vcard_sql).
+
+-compile([{parse_transform, ejabberd_sql_pt}]).
+
+-behaviour(mod_vcard).
+
+%% API
+-export([init/2, get_vcard/2, set_vcard/4, search/4, remove_user/2,
+	 import/1, import/2, export/1]).
+
+-include("jlib.hrl").
+-include("mod_vcard.hrl").
+-include("logger.hrl").
+-include("ejabberd_sql_pt.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+get_vcard(LUser, LServer) ->
+    case catch odbc_queries:get_vcard(LServer, LUser) of
+	{selected, [{SVCARD}]} ->
+	    case fxml_stream:parse_element(SVCARD) of
+		{error, _Reason} -> error;
+		VCARD -> [VCARD]
+	    end;
+	{selected, []} -> [];
+	_ -> error
+    end.
+
+set_vcard(LUser, LServer, VCARD,
+	  #vcard_search{user = {User, _},
+			fn = FN,
+			lfn = LFN,
+			family = Family,
+			lfamily = LFamily,
+			given = Given,
+			lgiven = LGiven,
+			middle = Middle,
+			lmiddle = LMiddle,
+			nickname = Nickname,
+			lnickname = LNickname,
+			bday = BDay,
+			lbday = LBDay,
+			ctry = CTRY,
+			lctry = LCTRY,
+			locality = Locality,
+			llocality = LLocality,
+			email = EMail,
+			lemail = LEMail,
+			orgname = OrgName,
+			lorgname = LOrgName,
+			orgunit = OrgUnit,
+			lorgunit = LOrgUnit}) ->
+    SVCARD = fxml:element_to_binary(VCARD),
+    odbc_queries:set_vcard(LServer, LUser, BDay, CTRY,
+			   EMail, FN, Family, Given, LBDay,
+			   LCTRY, LEMail, LFN, LFamily,
+			   LGiven, LLocality, LMiddle,
+			   LNickname, LOrgName, LOrgUnit,
+			   Locality, Middle, Nickname, OrgName,
+			   OrgUnit, SVCARD, User).
+
+search(LServer, Data, AllowReturnAll, MaxMatch) ->
+    MatchSpec = make_matchspec(LServer, Data),
+    if (MatchSpec == <<"">>) and not AllowReturnAll -> [];
+       true ->
+	    Limit = case MaxMatch of
+			infinity ->
+			    <<"">>;
+			Val ->
+			    [<<" LIMIT ">>, jlib:integer_to_binary(Val)]
+		    end,
+	   case catch ejabberd_odbc:sql_query(
+			LServer,
+			[<<"select username, fn, family, given, "
+			   "middle,        nickname, bday, ctry, "
+			   "locality,        email, orgname, orgunit "
+			   "from vcard_search ">>,
+			 MatchSpec, Limit, <<";">>]) of
+	       {selected,
+		[<<"username">>, <<"fn">>, <<"family">>, <<"given">>,
+		 <<"middle">>, <<"nickname">>, <<"bday">>, <<"ctry">>,
+		 <<"locality">>, <<"email">>, <<"orgname">>,
+		 <<"orgunit">>], Rs} when is_list(Rs) ->
+		   Rs;
+	       Error ->
+		   ?ERROR_MSG("~p", [Error]), []
+	   end
+    end.
+
+remove_user(LUser, LServer) ->
+    ejabberd_odbc:sql_transaction(
+      LServer,
+      fun() ->
+              ejabberd_odbc:sql_query_t(
+                ?SQL("delete from vcard where username=%(LUser)s")),
+              ejabberd_odbc:sql_query_t(
+                ?SQL("delete from vcard_search where lusername=%(LUser)s"))
+      end).
+
+export(_Server) ->   
+    [{vcard,
+      fun(Host, #vcard{us = {LUser, LServer}, vcard = VCARD})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              SVCARD =
+                  ejabberd_odbc:escape(fxml:element_to_binary(VCARD)),
+              [[<<"delete from vcard where username='">>, Username, <<"';">>],
+               [<<"insert into vcard(username, vcard) values ('">>,
+                Username, <<"', '">>, SVCARD, <<"');">>]];
+         (_Host, _R) ->
+              []
+      end},
+     {vcard_search,
+      fun(Host, #vcard_search{user = {User, LServer}, luser = LUser,
+                              fn = FN, lfn = LFN, family = Family,
+                              lfamily = LFamily, given = Given,
+                              lgiven = LGiven, middle = Middle,
+                              lmiddle = LMiddle, nickname = Nickname,
+                              lnickname = LNickname, bday = BDay,
+                              lbday = LBDay, ctry = CTRY, lctry = LCTRY,
+                              locality = Locality, llocality = LLocality,
+                              email = EMail, lemail = LEMail,
+                              orgname = OrgName, lorgname = LOrgName,
+                              orgunit = OrgUnit, lorgunit = LOrgUnit})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(User),
+              LUsername = ejabberd_odbc:escape(LUser),
+              SFN = ejabberd_odbc:escape(FN),
+              SLFN = ejabberd_odbc:escape(LFN),
+              SFamily = ejabberd_odbc:escape(Family),
+              SLFamily = ejabberd_odbc:escape(LFamily),
+              SGiven = ejabberd_odbc:escape(Given),
+              SLGiven = ejabberd_odbc:escape(LGiven),
+              SMiddle = ejabberd_odbc:escape(Middle),
+              SLMiddle = ejabberd_odbc:escape(LMiddle),
+              SNickname = ejabberd_odbc:escape(Nickname),
+              SLNickname = ejabberd_odbc:escape(LNickname),
+              SBDay = ejabberd_odbc:escape(BDay),
+              SLBDay = ejabberd_odbc:escape(LBDay),
+              SCTRY = ejabberd_odbc:escape(CTRY),
+              SLCTRY = ejabberd_odbc:escape(LCTRY),
+              SLocality = ejabberd_odbc:escape(Locality),
+              SLLocality = ejabberd_odbc:escape(LLocality),
+              SEMail = ejabberd_odbc:escape(EMail),
+              SLEMail = ejabberd_odbc:escape(LEMail),
+              SOrgName = ejabberd_odbc:escape(OrgName),
+              SLOrgName = ejabberd_odbc:escape(LOrgName),
+              SOrgUnit = ejabberd_odbc:escape(OrgUnit),
+              SLOrgUnit = ejabberd_odbc:escape(LOrgUnit),
+              [[<<"delete from vcard_search where lusername='">>,
+                LUsername, <<"';">>],
+               [<<"insert into vcard_search(        username, "
+                  "lusername, fn, lfn, family, lfamily, "
+                  "       given, lgiven, middle, lmiddle, "
+                  "nickname, lnickname,        bday, lbday, "
+                  "ctry, lctry, locality, llocality,   "
+                  "     email, lemail, orgname, lorgname, "
+                  "orgunit, lorgunit)values (">>,
+                <<"        '">>, Username, <<"', '">>, LUsername,
+                <<"',        '">>, SFN, <<"', '">>, SLFN,
+                <<"',        '">>, SFamily, <<"', '">>, SLFamily,
+                <<"',        '">>, SGiven, <<"', '">>, SLGiven,
+                <<"',        '">>, SMiddle, <<"', '">>, SLMiddle,
+                <<"',        '">>, SNickname, <<"', '">>, SLNickname,
+                <<"',        '">>, SBDay, <<"', '">>, SLBDay,
+                <<"',        '">>, SCTRY, <<"', '">>, SLCTRY,
+                <<"',        '">>, SLocality, <<"', '">>, SLLocality,
+                <<"',        '">>, SEMail, <<"', '">>, SLEMail,
+                <<"',        '">>, SOrgName, <<"', '">>, SLOrgName,
+                <<"',        '">>, SOrgUnit, <<"', '">>, SLOrgUnit,
+                <<"');">>]];
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select username, vcard from vcard;">>,
+      fun([LUser, SVCard]) ->
+              #xmlel{} = VCARD = fxml_stream:parse_element(SVCard),
+              #vcard{us = {LUser, LServer}, vcard = VCARD}
+      end},
+     {<<"select username, lusername, fn, lfn, family, lfamily, "
+        "given, lgiven, middle, lmiddle, nickname, lnickname, "
+        "bday, lbday, ctry, lctry, locality, llocality, email, "
+        "lemail, orgname, lorgname, orgunit, lorgunit from vcard_search;">>,
+      fun([User, LUser, FN, LFN,
+           Family, LFamily, Given, LGiven,
+           Middle, LMiddle, Nickname, LNickname,
+           BDay, LBDay, CTRY, LCTRY, Locality, LLocality,
+           EMail, LEMail, OrgName, LOrgName, OrgUnit, LOrgUnit]) ->
+              #vcard_search{us = {LUser, LServer},
+                            user = {User, LServer}, luser = LUser,
+                            fn = FN, lfn = LFN, family = Family,
+                            lfamily = LFamily, given = Given,
+                            lgiven = LGiven, middle = Middle,
+                            lmiddle = LMiddle, nickname = Nickname,
+                            lnickname = LNickname, bday = BDay,
+                            lbday = LBDay, ctry = CTRY, lctry = LCTRY,
+                            locality = Locality, llocality = LLocality,
+                            email = EMail, lemail = LEMail,
+                            orgname = OrgName, lorgname = LOrgName,
+                            orgunit = OrgUnit, lorgunit = LOrgUnit}
+      end}].
+
+import(_, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+make_matchspec(LServer, Data) ->
+    filter_fields(Data, <<"">>, LServer).
+
+filter_fields([], Match, _LServer) ->
+    case Match of
+	<<"">> -> <<"">>;
+	_ -> [<<" where ">>, Match]
+    end;
+filter_fields([{SVar, [Val]} | Ds], Match, LServer)
+  when is_binary(Val) and (Val /= <<"">>) ->
+    LVal = mod_vcard:string2lower(Val),
+    NewMatch = case SVar of
+		   <<"user">> -> make_val(Match, <<"lusername">>, LVal);
+		   <<"fn">> -> make_val(Match, <<"lfn">>, LVal);
+		   <<"last">> -> make_val(Match, <<"lfamily">>, LVal);
+		   <<"first">> -> make_val(Match, <<"lgiven">>, LVal);
+		   <<"middle">> -> make_val(Match, <<"lmiddle">>, LVal);
+		   <<"nick">> -> make_val(Match, <<"lnickname">>, LVal);
+		   <<"bday">> -> make_val(Match, <<"lbday">>, LVal);
+		   <<"ctry">> -> make_val(Match, <<"lctry">>, LVal);
+		   <<"locality">> ->
+		       make_val(Match, <<"llocality">>, LVal);
+		   <<"email">> -> make_val(Match, <<"lemail">>, LVal);
+		   <<"orgname">> -> make_val(Match, <<"lorgname">>, LVal);
+		   <<"orgunit">> -> make_val(Match, <<"lorgunit">>, LVal);
+		   _ -> Match
+	       end,
+    filter_fields(Ds, NewMatch, LServer);
+filter_fields([_ | Ds], Match, LServer) ->
+    filter_fields(Ds, Match, LServer).
+
+make_val(Match, Field, Val) ->
+    Condition = case str:suffix(<<"*">>, Val) of
+		  true ->
+		      Val1 = str:substr(Val, 1, byte_size(Val) - 1),
+		      SVal = <<(ejabberd_odbc:escape_like(Val1))/binary,
+			       "%">>,
+		      [Field, <<" LIKE '">>, SVal, <<"'">>];
+		  _ ->
+		      SVal = ejabberd_odbc:escape(Val),
+		      [Field, <<" = '">>, SVal, <<"'">>]
+		end,
+    case Match of
+      <<"">> -> Condition;
+      _ -> [Match, <<" and ">>, Condition]
+    end.
diff --git a/src/mod_vcard_xupdate.erl b/src/mod_vcard_xupdate.erl
index 18fb09a5..198312c3 100644
--- a/src/mod_vcard_xupdate.erl
+++ b/src/mod_vcard_xupdate.erl
@@ -17,26 +17,22 @@
 
 -include("ejabberd.hrl").
 -include("logger.hrl").
-
+-include("mod_vcard_xupdate.hrl").
 -include("jlib.hrl").
 
--record(vcard_xupdate, {us = {<<>>, <<>>} :: {binary(), binary()},
-                        hash = <<>>       :: binary()}).
+-callback init(binary(), gen_mod:opts()) -> any().
+-callback import(binary(), #vcard_xupdate{}) -> ok | pass.
+-callback add_xupdate(binary(), binary(), binary()) -> {atomic, any()}.
+-callback get_xupdate(binary(), binary()) -> binary() | undefined.
+-callback remove_xupdate(binary(), binary()) -> {atomic, any()}.
 
 %%====================================================================
 %% gen_mod callbacks
 %%====================================================================
 
 start(Host, Opts) ->
-    case gen_mod:db_type(Host, Opts) of
-      mnesia ->
-	  mnesia:create_table(vcard_xupdate,
-			      [{disc_copies, [node()]},
-			       {attributes,
-				record_info(fields, vcard_xupdate)}]),
-          update_table();
-      _ -> ok
-    end,
+    Mod = gen_mod:db_mod(Host, Opts, ?MODULE),
+    Mod:init(Host, Opts),
     ejabberd_hooks:add(c2s_update_presence, Host, ?MODULE,
 		       update_presence, 100),
     ejabberd_hooks:add(vcard_set, Host, ?MODULE, vcard_set,
@@ -79,75 +75,16 @@ vcard_set(LUser, LServer, VCARD) ->
 %%====================================================================
 
 add_xupdate(LUser, LServer, Hash) ->
-    add_xupdate(LUser, LServer, Hash,
-		gen_mod:db_type(LServer, ?MODULE)).
-
-add_xupdate(LUser, LServer, Hash, mnesia) ->
-    F = fun () ->
-		mnesia:write(#vcard_xupdate{us = {LUser, LServer},
-					    hash = Hash})
-	end,
-    mnesia:transaction(F);
-add_xupdate(LUser, LServer, Hash, riak) ->
-    {atomic, ejabberd_riak:put(#vcard_xupdate{us = {LUser, LServer},
-                                              hash = Hash},
-			       vcard_xupdate_schema())};
-add_xupdate(LUser, LServer, Hash, odbc) ->
-    Username = ejabberd_odbc:escape(LUser),
-    SHash = ejabberd_odbc:escape(Hash),
-    F = fun () ->
-		odbc_queries:update_t(<<"vcard_xupdate">>,
-				      [<<"username">>, <<"hash">>],
-				      [Username, SHash],
-				      [<<"username='">>, Username, <<"'">>])
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:add_xupdate(LUser, LServer, Hash).
 
 get_xupdate(LUser, LServer) ->
-    get_xupdate(LUser, LServer,
-		gen_mod:db_type(LServer, ?MODULE)).
-
-get_xupdate(LUser, LServer, mnesia) ->
-    case mnesia:dirty_read(vcard_xupdate, {LUser, LServer})
-	of
-      [#vcard_xupdate{hash = Hash}] -> Hash;
-      _ -> undefined
-    end;
-get_xupdate(LUser, LServer, riak) ->
-    case ejabberd_riak:get(vcard_xupdate, vcard_xupdate_schema(),
-			   {LUser, LServer}) of
-        {ok, #vcard_xupdate{hash = Hash}} -> Hash;
-        _ -> undefined
-    end;
-get_xupdate(LUser, LServer, odbc) ->
-    Username = ejabberd_odbc:escape(LUser),
-    case ejabberd_odbc:sql_query(LServer,
-				 [<<"select hash from vcard_xupdate where "
-				    "username='">>,
-				  Username, <<"';">>])
-	of
-      {selected, [<<"hash">>], [[Hash]]} -> Hash;
-      _ -> undefined
-    end.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:get_xupdate(LUser, LServer).
 
 remove_xupdate(LUser, LServer) ->
-    remove_xupdate(LUser, LServer,
-		   gen_mod:db_type(LServer, ?MODULE)).
-
-remove_xupdate(LUser, LServer, mnesia) ->
-    F = fun () ->
-		mnesia:delete({vcard_xupdate, {LUser, LServer}})
-	end,
-    mnesia:transaction(F);
-remove_xupdate(LUser, LServer, riak) ->
-    {atomic, ejabberd_riak:delete(vcard_xupdate, {LUser, LServer})};
-remove_xupdate(LUser, LServer, odbc) ->
-    Username = ejabberd_odbc:escape(LUser),
-    F = fun () ->
-		ejabberd_odbc:sql_query_t([<<"delete from vcard_xupdate where username='">>,
-					   Username, <<"';">>])
-	end,
-    ejabberd_odbc:sql_transaction(LServer, F).
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:remove_xupdate(LUser, LServer).
 
 %%%----------------------------------------------------------------------
 %%% Presence stanza rebuilding
@@ -184,53 +121,17 @@ build_xphotoel(User, Host) ->
 	   attrs = [{<<"xmlns">>, ?NS_VCARD_UPDATE}],
 	   children = PhotoEl}.
 
-vcard_xupdate_schema() ->
-    {record_info(fields, vcard_xupdate), #vcard_xupdate{}}.
-
-update_table() ->
-    Fields = record_info(fields, vcard_xupdate),
-    case mnesia:table_info(vcard_xupdate, attributes) of
-      Fields ->
-            ejabberd_config:convert_table_to_binary(
-              vcard_xupdate, Fields, set,
-              fun(#vcard_xupdate{us = {U, _}}) -> U end,
-              fun(#vcard_xupdate{us = {U, S}, hash = Hash} = R) ->
-                      R#vcard_xupdate{us = {iolist_to_binary(U),
-                                            iolist_to_binary(S)},
-                                      hash = iolist_to_binary(Hash)}
-              end);
-        _ ->            
-            ?INFO_MSG("Recreating vcard_xupdate table", []),
-            mnesia:transform_table(vcard_xupdate, ignore, Fields)
-    end.
-
-export(_Server) ->
-    [{vcard_xupdate,
-      fun(Host, #vcard_xupdate{us = {LUser, LServer}, hash = Hash})
-            when LServer == Host ->
-              Username = ejabberd_odbc:escape(LUser),
-              SHash = ejabberd_odbc:escape(Hash),
-              [[<<"delete from vcard_xupdate where username='">>,
-                Username, <<"';">>],
-               [<<"insert into vcard_xupdate(username, "
-                  "hash) values ('">>,
-                Username, <<"', '">>, SHash, <<"');">>]];
-         (_Host, _R) ->
-              []
-      end}].
+export(LServer) ->
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:export(LServer).
 
 import(LServer) ->
-    [{<<"select username, hash from vcard_xupdate;">>,
-      fun([LUser, Hash]) ->
-              #vcard_xupdate{us = {LUser, LServer}, hash = Hash}
-      end}].
-
-import(_LServer, mnesia, #vcard_xupdate{} = R) ->
-    mnesia:dirty_write(R);
-import(_LServer, riak, #vcard_xupdate{} = R) ->
-    ejabberd_riak:put(R, vcard_xupdate_schema());
-import(_, _, _) ->
-    pass.
+    Mod = gen_mod:db_mod(LServer, ?MODULE),
+    Mod:import(LServer).
+
+import(LServer, DBType, LA) ->
+    Mod = gen_mod:db_mod(DBType, ?MODULE),
+    Mod:import(LServer, LA).
 
 mod_opt_type(db_type) -> fun gen_mod:v_db/1;
 mod_opt_type(_) -> [db_type].
diff --git a/src/mod_vcard_xupdate_mnesia.erl b/src/mod_vcard_xupdate_mnesia.erl
new file mode 100644
index 00000000..f1b1693e
--- /dev/null
+++ b/src/mod_vcard_xupdate_mnesia.erl
@@ -0,0 +1,69 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_vcard_xupdate_mnesia).
+-behaviour(mod_vcard_xupdate).
+
+%% API
+-export([init/2, import/2, add_xupdate/3, get_xupdate/2, remove_xupdate/2]).
+
+-include("mod_vcard_xupdate.hrl").
+-include("logger.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    mnesia:create_table(vcard_xupdate,
+			[{disc_copies, [node()]},
+			 {attributes,
+			  record_info(fields, vcard_xupdate)}]),
+    update_table().
+
+add_xupdate(LUser, LServer, Hash) ->
+    F = fun () ->
+		mnesia:write(#vcard_xupdate{us = {LUser, LServer},
+					    hash = Hash})
+	end,
+    mnesia:transaction(F).
+
+get_xupdate(LUser, LServer) ->
+    case mnesia:dirty_read(vcard_xupdate, {LUser, LServer})
+	of
+      [#vcard_xupdate{hash = Hash}] -> Hash;
+      _ -> undefined
+    end.
+
+remove_xupdate(LUser, LServer) ->
+    F = fun () ->
+		mnesia:delete({vcard_xupdate, {LUser, LServer}})
+	end,
+    mnesia:transaction(F).
+
+import(_LServer, #vcard_xupdate{} = R) ->
+    mnesia:dirty_write(R).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+update_table() ->
+    Fields = record_info(fields, vcard_xupdate),
+    case mnesia:table_info(vcard_xupdate, attributes) of
+      Fields ->
+            ejabberd_config:convert_table_to_binary(
+              vcard_xupdate, Fields, set,
+              fun(#vcard_xupdate{us = {U, _}}) -> U end,
+              fun(#vcard_xupdate{us = {U, S}, hash = Hash} = R) ->
+                      R#vcard_xupdate{us = {iolist_to_binary(U),
+                                            iolist_to_binary(S)},
+                                      hash = iolist_to_binary(Hash)}
+              end);
+        _ ->            
+            ?INFO_MSG("Recreating vcard_xupdate table", []),
+            mnesia:transform_table(vcard_xupdate, ignore, Fields)
+    end.
diff --git a/src/mod_vcard_xupdate_riak.erl b/src/mod_vcard_xupdate_riak.erl
new file mode 100644
index 00000000..129a0c6a
--- /dev/null
+++ b/src/mod_vcard_xupdate_riak.erl
@@ -0,0 +1,44 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_vcard_xupdate_riak).
+
+%% API
+-export([init/2, import/2, add_xupdate/3, get_xupdate/2, remove_xupdate/2]).
+
+-include("mod_vcard_xupdate.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+add_xupdate(LUser, LServer, Hash) ->
+    {atomic, ejabberd_riak:put(#vcard_xupdate{us = {LUser, LServer},
+                                              hash = Hash},
+			       vcard_xupdate_schema())}.
+
+get_xupdate(LUser, LServer) ->
+    case ejabberd_riak:get(vcard_xupdate, vcard_xupdate_schema(),
+			   {LUser, LServer}) of
+        {ok, #vcard_xupdate{hash = Hash}} -> Hash;
+        _ -> undefined
+    end.
+
+remove_xupdate(LUser, LServer) ->
+    {atomic, ejabberd_riak:delete(vcard_xupdate, {LUser, LServer})}.
+
+import(_LServer, #vcard_xupdate{} = R) ->
+    ejabberd_riak:put(R, vcard_xupdate_schema()).
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+vcard_xupdate_schema() ->
+    {record_info(fields, vcard_xupdate), #vcard_xupdate{}}.
diff --git a/src/mod_vcard_xupdate_sql.erl b/src/mod_vcard_xupdate_sql.erl
new file mode 100644
index 00000000..d580b151
--- /dev/null
+++ b/src/mod_vcard_xupdate_sql.erl
@@ -0,0 +1,79 @@
+%%%-------------------------------------------------------------------
+%%% @author Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%% @copyright (C) 2016, Evgeny Khramtsov
+%%% @doc
+%%%
+%%% @end
+%%% Created : 13 Apr 2016 by Evgeny Khramtsov <ekhramtsov@process-one.net>
+%%%-------------------------------------------------------------------
+-module(mod_vcard_xupdate_sql).
+
+%% API
+-export([init/2, import/2, add_xupdate/3, get_xupdate/2, remove_xupdate/2,
+	 import/1, export/1]).
+
+-include("mod_vcard_xupdate.hrl").
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+init(_Host, _Opts) ->
+    ok.
+
+add_xupdate(LUser, LServer, Hash) ->
+    Username = ejabberd_odbc:escape(LUser),
+    SHash = ejabberd_odbc:escape(Hash),
+    F = fun () ->
+		odbc_queries:update_t(<<"vcard_xupdate">>,
+				      [<<"username">>, <<"hash">>],
+				      [Username, SHash],
+				      [<<"username='">>, Username, <<"'">>])
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+get_xupdate(LUser, LServer) ->
+    Username = ejabberd_odbc:escape(LUser),
+    case ejabberd_odbc:sql_query(LServer,
+				 [<<"select hash from vcard_xupdate where "
+				    "username='">>,
+				  Username, <<"';">>])
+	of
+      {selected, [<<"hash">>], [[Hash]]} -> Hash;
+      _ -> undefined
+    end.
+
+remove_xupdate(LUser, LServer) ->
+    Username = ejabberd_odbc:escape(LUser),
+    F = fun () ->
+		ejabberd_odbc:sql_query_t([<<"delete from vcard_xupdate where username='">>,
+					   Username, <<"';">>])
+	end,
+    ejabberd_odbc:sql_transaction(LServer, F).
+
+export(_Server) ->
+    [{vcard_xupdate,
+      fun(Host, #vcard_xupdate{us = {LUser, LServer}, hash = Hash})
+            when LServer == Host ->
+              Username = ejabberd_odbc:escape(LUser),
+              SHash = ejabberd_odbc:escape(Hash),
+              [[<<"delete from vcard_xupdate where username='">>,
+                Username, <<"';">>],
+               [<<"insert into vcard_xupdate(username, "
+                  "hash) values ('">>,
+                Username, <<"', '">>, SHash, <<"');">>]];
+         (_Host, _R) ->
+              []
+      end}].
+
+import(LServer) ->
+    [{<<"select username, hash from vcard_xupdate;">>,
+      fun([LUser, Hash]) ->
+              #vcard_xupdate{us = {LUser, LServer}, hash = Hash}
+      end}].
+
+import(_LServer, _) ->
+    pass.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================