17.7.2 InnoDB Transaction Model

17.7.2.1 Transaction Isolation Levels

17.7.2.2 autocommit, Commit, and Rollback

17.7.2.3 Consistent Nonlocking Reads

17.7.2.4 Locking Reads

The InnoDB transaction model aims to 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.