18.104.22.168 Restrictions on Replication with GTIDs
Because GTID-based replication is dependent on transactions, some features otherwise available in MySQL are not supported when using it. This section provides information about restrictions on and limitations of replication with GTIDs.
Updates involving nontransactional storage engines. When using GTIDs, updates to tables using nontransactional storage engines such as
MyISAM cannot be made in the same statement or transaction as updates to tables using transactional storage engines such as
This restriction is due to the fact that updates to tables that use a nontransactional storage engine mixed with updates to tables that use a transactional storage engine within the same transaction can result in multiple GTIDs being assigned to the same transaction.
Such problems can also occur when the source and the replica use different storage engines for their respective versions of the same table, where one storage engine is transactional and the other is not. Also be aware that triggers that are defined to operate on nontransactional tables can be the cause of these problems.
In any of the cases just mentioned, the one-to-one correspondence between transactions and GTIDs is broken, with the result that GTID-based replication cannot function correctly.
CREATE TABLE ... SELECT statements.
CREATE TABLE ... SELECT statements are not allowed when using GTID-based replication. When
binlog_format is set to STATEMENT, a
CREATE TABLE ... SELECT statement is recorded in the binary log as one transaction with one GTID, but if ROW format is used, the statement is recorded as two transactions with two GTIDs. If a source used STATEMENT format and a replica used ROW format, the replica would be unable to handle the transaction correctly, therefore the
CREATE TABLE ... SELECT statement is disallowed with GTIDs to prevent this scenario.
CREATE TEMPORARY TABLE and
DROP TEMPORARY TABLE statements are not supported inside transactions, procedures, functions, and triggers when using GTIDs (that is, when the
enforce_gtid_consistency system variable is set to
ON). It is possible to use these statements with GTIDs enabled, but only outside of any transaction, and only with
Preventing execution of unsupported statements. To prevent execution of statements that would cause GTID-based replication to fail, all servers must be started with the
--enforce-gtid-consistency option when enabling GTIDs. This causes statements of any of the types discussed previously in this section to fail with an error.
--enforce-gtid-consistency only takes effect if binary logging takes place for a statement. If binary logging is disabled on the server, or if statements are not written to the binary log because they are removed by a filter, GTID consistency is not checked or enforced for the statements that are not logged.
For information about other required startup options when enabling GTIDs, see Section 22.214.171.124, “Setting Up Replication Using GTIDs”.
sql_slave_skip_counter is not supported when using GTIDs. If you need to skip transactions, use the value of the source's
gtid_executed variable instead. For instructions, see Section 126.96.36.199, “Skipping Transactions”.
Ignoring servers. The IGNORE_SERVER_IDS option of the
CHANGE MASTER TO statement is deprecated when using GTIDs, because transactions that have already been applied are automatically ignored. Before starting GTID-based replication, check for and clear all ignored server ID lists that have previously been set on the servers involved. The
SHOW SLAVE STATUS statement, which can be issued for individual channels, displays the list of ignored server IDs if there is one. If there is no list, the
Replicate_Ignore_Server_Ids field is blank.
GTID mode and mysqldump. It is possible to import a dump made using mysqldump into a MySQL server running with GTID mode enabled, provided that there are no GTIDs in the target server's binary log.