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