InnoDB Locking and Transaction Model This occurs when a rollback segment assigned to a transaction runs out of undo slots. In such cases, try rerunning the transaction. When transactions perform operations on temporary tables, the number of concurrent read-write transactions that  InnoDB  is capable of supporting is constrained by the number of rollback segments allocated to the global temporary tablespace, which is 128 by default. •If each transaction performs either an  INSERT or  an  UPDATE  or  DELETE  operation, the number of concurrent read-write transactions that  InnoDB  is capable of supporting is: •If each transaction performs an  INSERT and  an  UPDATE  or  DELETE  operation, the number of concurrent read-write transactions that  InnoDB  is capable of supporting is: •If each transaction performs an  INSERT  operation on a temporary table, the number of concurrent read- write transactions that  InnoDB  is capable of supporting is: •If each transaction performs an  INSERT and  an  UPDATE  or  DELETE  operation on a temporary table, the number of concurrent read-write transactions that  InnoDB  is capable of supporting is: (innodb_page_size / 16) * innodb_rollback_segments * number of undo tablespaces (innodb_page_size / 16 / 2) * innodb_rollback_segments * number of undo tablespaces (innodb_page_size / 16) * innodb_rollback_segments (innodb_page_size / 16 / 2) * innodb_rollback_segments To implement a large-scale, busy, or highly reliable database application, to port substantial code from a different database system, or to tune MySQL performance, it is important to understand  InnoDB  locking and the  InnoDB  transaction model. This section discusses several topics related to  InnoDB  locking and the  InnoDB  transaction model with which you should be familiar. 15.7 InnoDB Locking and Transaction Model •Section 15.7.1, “InnoDB Locking”  describes lock types used by  InnoDB . •Section 15.7.2, “InnoDB Transaction Model”  describes transaction isolation levels and the locking strategies used by each. It also discusses the use of  autocommit , consistent non-locking reads, and locking reads. •Section 15.7.3, “Locks Set by Different SQL Statements in InnoDB”  discusses specific types of locks set in  InnoDB  for various statements. •Section 15.7.4, “Phantom Rows”  describes how  InnoDB  uses next-key locking to avoid phantom rows. •Section 15.7.5, “Deadlocks in InnoDB”  provides a deadlock example, discusses deadlock detection, and provides tips for minimizing and handling deadlocks in  InnoDB . •Shared and Exclusive Locks •Intention Locks This section describes lock types used by  InnoDB . 15.7.1 InnoDB Locking 3080