Lightning Memory-Mapped Database: Difference between revisions

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'''Lightning Memory-Mapped Database''' (LMDB) is a [[software library]] that provides a high-performancean embedded transactional database in the form of a [[key-value store]]. LMDB is written in [[C (programming language)|C]] with [[#API and uses|API bindings]] for several [[programming language]]s. 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 at the end of the database (MDB_APPEND) whichwithout giveschecking afor dramatic write performance increase over other similar storesconsistency.<ref name="auto">[http://symas.com/mdb/doc/group__internal.html LMDB Reference Guide] {{Webarchive|url=https://web.archive.org/web/20141020182433/http://symas.com/mdb/doc/group__internal.html |date=2014-10-20 }}. Retrieved on 2014-10-19</ref> LMDB is not a [[relational database]], it is strictly a key-value store like [[Berkeley DB]] and [[DBM (computing)|dbm]].

LMDB may also be used [[#Concurrency|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 ''not'' 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.