IOWOW is persistent key-value database engine based on skip list data
structure.  Some of its features and limitations:

  - Support of multiple key-value databases within a single file
  - Native support of integer keys
  - Write Ahead Logging (WAL)
  - Support of record values represented as sorted array of integers
  - Ultra-fast sequential traversal of database records
  - Compound keys support
  - Good performance comparing to main competitors (LMDB, LevelDB,
    Kyoto Cabinet)
  - Tiny C11 library (200 KB), easily embeddable into any software
  - Maximum storage file size is 512 GB, maximum size of a single
    key+value record is 255 MB

WWW: http://iowow.io/