An ultra-fast, ultra-compact, crash-proof key-value embedded data store.

Symas LMDB is an extraordinarily fast, memory-efficient database we developed for the OpenLDAP Project. With memory-mapped files, it has the read performance of a pure in-memory database while retaining the persistence of standard disk-based databases.
Bottom line, with only 32KB of object code, LMDB may seem tiny. But it’s the right 32KB. Compact and efficient are two sides of a coin; that’s part of what makes LMDB so powerful.

Explore Capabilities

• Ordered-map interface
  • keys are always sorted; range lookups are supported
• Fully-transactional
  • full ACID semantics with MVCC
• Reader/writer transactions
  • readers don’t block writers; writers don’t block readers
• Fully serialized writers
  • writes are always deadlock-free
• Extremely cheap read transactions
  • can be performed using no mallocs or any other blocking calls
• Multi-thread and multi-process concurrency supported
  • Environments may be opened by multiple processes on the same host
• Multiple sub-databases may be created
  • transactions cover all sub-databases
• Memory-mapped
  • allows for zero-copy lookup and iteration
• Maintenance-free 
  • no external process or background cleanup or compaction required
• Crash-proof
  • no logs or crash recovery procedures required
• No application-level caching
  • LMDB fully exploits the operating system’s buffer cache
• 32KB of object code and 6KLOC of C
  • fits in CPU L1 cache for maximum performance