InnoDB provides MySQL with a transaction-safe (ACID compliant) storage engine with commit, rollback, and crash recovery capabilities. InnoDB does locking on the row level and also provides an Oracle-style consistent non-locking read in SELECT statements. These features increase multi-user concurrency and performance. There is no need for lock escalation in InnoDB because row-level locks in InnoDB fit in very little space. InnoDB also supports FOREIGN KEY constraints. In SQL queries you can freely mix InnoDB type tables with other table types of MySQL, even within the same query.

InnoDB has been designed for maximum performance when processing large data volumes. Its CPU efficiency is probably not matched by any other disk-based relational database engine.

Fully integrated with MySQL Server, the InnoDB storage engine maintains its own buffer pool for caching data and indexes in main memory. InnoDB stores its tables and indexes in a tablespace, which may consist of several files (or raw disk partitions). This is different from, for example, MyISAM tables where each table is stored using separate files. InnoDB tables can be of any size even on operating systems where file size is limited to 2GB.

InnoDB is included in binary distributions by default as of MySQL 4.0. For information about InnoDB support in MySQL 3.23, see the section called “InnoDB in MySQL 3.23”.

InnoDB is used in production at numerous large database sites requiring high performance. The famous Internet news site Slashdot.org runs on InnoDB. Mytrix, Inc. stores over 1TB of data in InnoDB, and another site handles an average load of 800 inserts/updates per second in InnoDB.

InnoDB is published under the same GNU GPL License Version 2 (of June 1991) as MySQL. If you distribute MySQL/InnoDB, and your application does not satisfy the provisions of the GPL license, you must purchase a commercial MySQL Pro license from https://order.mysql.com/?sub=pg&pg_no=1.