SET TRANSACTION

Purpose

Sets the transaction isolation level.

OceanBase Database in MySQL mode supports the Read Committed and Repeatable Read isolation levels. The default isolation level is Read Committed.

• You cannot set the isolation level during a transaction. Otherwise, an error will be returned.

  ERROR:OBE-01453: SET TRANSACTION must be first statement of transaction

• When the Serializable isolation level is enabled, the Global Timestamp Service (GTS) must be enabled.

• The session must maintain the session-level transaction isolation level. When a transaction is started, the session-level transaction isolation level is obtained. This isolation level can be overridden by the transaction-level isolation level.

Syntax

SET [GLOBAL | SESSION | LOCAL] TRANSACTION trans_opt

trans_opt:
   transaction_access_mode
 | isolation_level
 | transaction_access_mode, isolation_level
 | isolation_level, transaction_access_mode

transaction_access_mode:
    [READ ONLY | READ WRITE]

isolation_level:
    ISOLATION LEVEL {
      READ UNCOMMITTED
    | READ COMMITTED
    | REPEATABLE READ
    | SERIALIZABLE
  }

Parameters

Examples

• Set the transaction isolation level of the next transaction in the current session to Read Committed.

  obclient> SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
  

• Set the transaction isolation level of the current session to Repeatable Read.

  obclient> SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;