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12.3.7.2. XA Transaction States

An XA transaction progresses through the following states:

  1. Use XA START to start an XA transaction and put it in the ACTIVE state.

  2. For an ACTIVE XA transaction, issue the SQL statements that make up the transaction, and then issue an XA END statement. XA END puts the transaction in the IDLE state.

  3. For an IDLE XA transaction, you can issue either an XA PREPARE statement or an XA COMMIT ... ONE PHASE statement:

    • XA PREPARE puts the transaction in the PREPARED state. An XA RECOVER statement at this point will include the transaction's xid value in its output, because XA RECOVER lists all XA transactions that are in the PREPARED state.

    • XA COMMIT ... ONE PHASE prepares and commits the transaction. The xid value will not be listed by XA RECOVER because the transaction terminates.

  4. For a PREPARED XA transaction, you can issue an XA COMMIT statement to commit and terminate the transaction, or XA ROLLBACK to roll back and terminate the transaction.

Here is a simple XA transaction that inserts a row into a table as part of a global transaction: 

mysql> XA START 'xatest';
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO mytable (i) VALUES(10);
Query OK, 1 row affected (0.04 sec)

mysql> XA END 'xatest';
Query OK, 0 rows affected (0.00 sec)

mysql> XA PREPARE 'xatest';
Query OK, 0 rows affected (0.00 sec)

mysql> XA COMMIT 'xatest';
Query OK, 0 rows affected (0.00 sec)

Within the context of a given client connection, XA transactions and local (non-XA) transactions are mutually exclusive. For example, if XA START has been issued to begin an XA transaction, a local transaction cannot be started until the XA transaction has been committed or rolled back. Conversely, if a local transaction has been started with START TRANSACTION, no XA statements can be used until the transaction has been committed or rolled back.

Note that if an XA transaction is in the ACTIVE state, you cannot issue any statements that cause an implicit commit. That would violate the XA contract because you could not roll back the XA transaction. You will receive the following error if you try to execute such a statement: 

ERROR 1399 (XAE07): XAER_RMFAIL: The command cannot be executed
when global transaction is in the ACTIVE state

Statements to which the preceding remark applies are listed at Section 12.3.3, “Statements That Cause an Implicit Commit”.

MySQL Enterprise.  MySQL Enterprise subscribers will find more information on this subject in the Knowledge Base article, Can I Undo a Set of SQL Statements? To subscribe to MySQL Enterprise see http://www.mysql.com/products/enterprise/advisors.html.