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START TRANSACTION | TiDB SQL Statement Reference
An overview of the usage of START TRANSACTION for the TiDB database.
/docs/dev/sql-statements/sql-statement-start-transaction/
/docs/dev/reference/sql/statements/start-transaction/

START TRANSACTION

This statement starts a new transaction inside of TiDB. It is similar to the statement BEGIN.

In the absence of a START TRANSACTION statement, every statement will by default autocommit in its own transaction. This behavior ensures MySQL compatibility.

Synopsis

BeginTransactionStmt:

BeginTransactionStmt ::=
    'BEGIN' ( 'PESSIMISTIC' | 'OPTIMISTIC' )?
|   'START' 'TRANSACTION' ( 'READ' ( 'WRITE' | 'ONLY' ( ( 'WITH' 'TIMESTAMP' 'BOUND' TimestampBound )? | AsOfClause ) ) | 'WITH' 'CONSISTENT' 'SNAPSHOT' | 'WITH' 'CAUSAL' 'CONSISTENCY' 'ONLY' )?

AsOfClause ::=
    ( 'AS' 'OF' 'TIMESTAMP' Expression)

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

  • START TRANSACTION immediately starts a transaction inside TiDB. This differs from MySQL, where START TRANSACTION lazily creates a transaction. But START TRANSACTION in TiDB is equivalent to MySQL's START TRANSACTION WITH CONSISTENT SNAPSHOT.

  • The statement START TRANSACTION READ ONLY is parsed for compatibility with MySQL, but still allows write operations.

See also