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COMMIT

This statement commits a transaction inside of the TIDB server.

In the absence of a BEGIN or START TRANSACTION statement, the default behavior of TiDB is that every statement will be its own transaction and autocommit. This behavior ensures MySQL compatibility.

Synopsis

CommitStmt:

CommitStmt

CompletionTypeWithinTransaction:

CompletionTypeWithinTransaction

Examples

mysql> CREATE TABLE t1 (a int NOT NULL PRIMARY KEY);
Query OK, 0 rows affected (0.12 sec)

mysql> START TRANSACTION;
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO t1 VALUES (1);
Query OK, 1 row affected (0.00 sec)

mysql> COMMIT;
Query OK, 0 rows affected (0.01 sec)

MySQL compatibility

  • By default, TiDB 3.0.8 and later versions use Pessimistic Locking. When using Optimistic Locking, it is important to consider that a COMMIT statement might fail because rows have been modified by another transaction.
  • When Optimistic Locking is enabled, UNIQUE and PRIMARY KEY constraint checks are deferred until statement commit. This results in additional situations where a a COMMIT statement might fail. This behavior can be changed by setting tidb_constraint_check_in_place=TRUE.
  • TiDB parses but ignores the syntax ROLLBACK AND [NO] RELEASE. This functionality is used in MySQL to disconnect the client session immediately after committing the transaction. In TiDB, it is recommended to instead use the mysql_close() functionality of your client driver.
  • TiDB parses but ignores the syntax ROLLBACK AND [NO] CHAIN. This functionality is used in MySQL to immediately start a new transaction with the same isolation level while the current transaction is being committed. In TiDB, it is recommended to instead start a new transaction.

See also