13.3.3 Statements That Cause an Implicit Commit

The statements listed in this section (and any synonyms for them) implicitly end any transaction active in the current session, as if you had done a COMMIT before executing the statement.

Most of these statements also cause an implicit commit after executing. The intent is to handle each such statement in its own special transaction because it cannot be rolled back anyway. Transaction-control and locking statements are exceptions: If an implicit commit occurs before execution, another does not occur after.

• Data definition language (DDL) statements that define or modify database objects. ALTER DATABASE ... UPGRADE DATA DIRECTORY NAME, ALTER EVENT, ALTER PROCEDURE, ALTER SERVER, ALTER TABLE, ALTER TABLESPACE, ALTER VIEW, CREATE DATABASE, CREATE EVENT, CREATE INDEX, CREATE PROCEDURE, CREATE SERVER, CREATE TABLE, CREATE TABLESPACE, CREATE TRIGGER, CREATE VIEW, DROP DATABASE, DROP EVENT, DROP INDEX, DROP PROCEDURE, DROP SERVER, DROP TABLE, DROP TABLESPACE, DROP TRIGGER, DROP VIEW, INSTALL PLUGIN, RENAME TABLE, TRUNCATE TABLE, UNINSTALL PLUGIN.

  ALTER FUNCTION, CREATE FUNCTION and DROP FUNCTION also cause an implicit commit when used with stored functions, but not with loadable functions. (ALTER FUNCTION can only be used with stored functions.)

  CREATE TABLE and DROP TABLE statements do not commit a transaction if the TEMPORARY keyword is used. (This does not apply to other operations on temporary tables such as ALTER TABLE and CREATE INDEX, which do cause a commit.) However, although no implicit commit occurs, neither can the statement be rolled back, which means that the use of such statements causes transactional atomicity to be violated. For example, if you use CREATE TEMPORARY TABLE and then roll back the transaction, the table remains in existence.

  The CREATE TABLE statement in InnoDB is processed as a single transaction. This means that a ROLLBACK from the user does not undo CREATE TABLE statements the user made during that transaction.

  CREATE TABLE ... SELECT causes an implicit commit before and after the statement is executed when you are creating nontemporary tables. (No commit occurs for CREATE TEMPORARY TABLE ... SELECT.)

• Statements that implicitly use or modify tables in the mysql database. ALTER USER, CREATE USER, DROP USER, GRANT, RENAME USER, REVOKE, SET PASSWORD.

• Transaction-control and locking statements. BEGIN, LOCK TABLES, SET autocommit = 1 (if the value is not already 1), START TRANSACTION, UNLOCK TABLES.

  UNLOCK TABLES commits a transaction only if any tables currently have been locked with LOCK TABLES to acquire nontransactional table locks. A commit does not occur for UNLOCK TABLES following FLUSH TABLES WITH READ LOCK because the latter statement does not acquire table-level locks.

  Transactions cannot be nested. This is a consequence of the implicit commit performed for any current transaction when you issue a START TRANSACTION statement or one of its synonyms.

  Statements that cause an implicit commit cannot be used in an XA transaction while the transaction is in an ACTIVE state.

  The BEGIN statement differs from the use of the BEGIN keyword that starts a BEGIN ... END compound statement. The latter does not cause an implicit commit. See Section 13.6.1, “BEGIN ... END Compound Statement”.

• Data loading statements. LOAD DATA. LOAD DATA causes an implicit commit only for tables using the NDB storage engine.

• Administrative statements. ANALYZE TABLE, CACHE INDEX, CHECK TABLE, FLUSH, LOAD INDEX INTO CACHE, OPTIMIZE TABLE, REPAIR TABLE, RESET.

• Replication control statements. START SLAVE, STOP SLAVE, RESET SLAVE, CHANGE MASTER TO.