Statements That Cause an Implicit Commit

The statements listed in this section (and any synonyms for them) implicitly end a transaction, as if you had done a COMMIT before executing the statement. As of MariaDB 5.5.3, most of these statements also cause an implicit commit after executing; for additional details, see the end of this section.

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

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

  ALTER TABLE, CREATE TABLE, and DROP TABLE do not commit a transaction if the TEMPORARY keyword is used. (This does not apply to other operations on temporary tables such as CREATE INDEX, which do cause a commit.) However, although no implicit commit occurs, neither can the statement be rolled back. Therefore, use of such statements will violate transaction atomicity: 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.) This is to prevent an issue during replication where the table could be created on the master after a rollback, but fail to be recorded in the binary log, and therefore not replicated to the slave. For more information, see Bug #22865.

• Statements that implicitly use or modify tables in the MariaDB database. 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 , "BEGIN ... END Compound-Statement Syntax".

• Data loading statements. LOAD DATA INFILE. LOAD DATA INFILE causes an implicit commit only for tables using the NDB storage engine. For more information, see Bug #11151.
• Administrative statements. ANALYZE TABLE, CACHE INDEX, CHECK TABLE, LOAD INDEX INTO CACHE, OPTIMIZE TABLE, REPAIR TABLE.

As of MariaDB 5.5.3, most statements that previously caused an implicit commit before executing also do so after executing. The intent is to handle each such statement in its own special transaction because it cannot be rolled back anyway. The following list provides additional details pertaining to this change:

• The CREATE TABLE variants (CREATE TABLE for InnoDB tables and CREATE TABLE ... SELECT) that previously were special cases no longer are so because CREATE TABLE uniformly causes an implicit commit before and after executing.
• The FLUSH and RESET statements cause an implicit commit.
• Transaction-control and locking statements behave as before.

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