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Lightning Memory-Mapped Database
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<ul> <li>Free and open-source software portal</li></ul> <p>Lightning Memory-Mapped Database (LMDB) is an embedded transactional <a href="/facts/Database/VYcpkevb">database</a> in the form of a <a href="/facts/Key-value_store/Yee8EIGE">key-value store</a>. LMDB is written in <a href="/facts/C_(programming_language)/Ky2No763">C</a> with API bindings for several <a href="/facts/Programming_language/cWTYbgWa">programming languages</a>. LMDB stores arbitrary key/data pairs as byte arrays, has a range-based search capability, supports multiple data items for a single key and has a special mode for appending records (MDB_APPEND) without checking for consistency. LMDB is not a <a href="/facts/Relational_database/pEKGmJLy">relational database</a>, it is strictly a key-value store like <a href="/facts/Berkeley_DB/lWwNrclz">Berkeley DB</a> and <a href="/facts/DBM_(computing)/CgBHvMEz">DBM</a>. </p><p>LMDB may also be used concurrently in a multi-threaded or multi-processing environment, with read performance scaling linearly by design. LMDB databases may have only one writer at a time, however unlike many similar key-value databases, write transactions do <i>not</i> block readers, nor do readers block writers. LMDB is also unusual in that multiple applications on the same system may simultaneously open and use the same LMDB store, as a means to scale up performance. Also, LMDB does not require a transaction log (thereby increasing write performance by not needing to write data twice) because it maintains data integrity inherently by design. </p>