14.7.2 InnoDB Transaction Model

14.7.2.1 Transaction Isolation Levels

14.7.2.2 autocommit, Commit, and Rollback

14.7.2.3 Consistent Nonlocking Reads

14.7.2.4 Locking Reads

The InnoDB transaction model aims combine the best properties of a multi-versioning database with traditional two-phase locking. InnoDB performs locking at the row level and runs queries as nonlocking consistent reads by default, in the style of Oracle. The lock information in InnoDB is stored space-efficiently so that lock escalation is not needed. Typically, several users are permitted to lock every row in InnoDB tables, or any random subset of the rows, without causing InnoDB memory exhaustion.