2.3.7 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 InnoDB.

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.  Prior to MySQL 8.0.21, 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. This restriction is lifted in MySQL 8.0.21 on storage engines that support atomic DDL. In this case, CREATE TABLE ... SELECT is recorded in the binary log as one transaction. For more information, see Atomic Data Definition Statement Support.

Temporary tables.  When binlog_format is set to STATEMENT, CREATE TEMPORARY TABLE and DROP TEMPORARY TABLE statements cannot be used inside transactions, procedures, functions, and triggers when GTIDs are in use on the server (that is, when the enforce_gtid_consistency system variable is set to ON). They can be used outside these contexts when GTIDs are in use, provided that autocommit=1 is set. From MySQL 8.0.13, when binlog_format is set to ROW or MIXED, CREATE TEMPORARY TABLE and DROP TEMPORARY TABLE statements are allowed inside a transaction, procedure, function, or trigger when GTIDs are in use. The statements are not written to the binary log and are therefore not replicated to replicas. The use of row-based replication means that the replicas remain in sync without the need to replicate temporary tables. If the removal of these statements from a transaction results in an empty transaction, the transaction is not written to the binary log.

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.

Note that --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 2.3.4, “Setting Up Replication Using GTIDs”.

Skipping transactions.  sql_replica_skip_counter or sql_slave_skip_counter is not available when using GTID-based replication. If you need to skip transactions, use the value of the source's gtid_executed variable instead. If you have enabled GTID assignment on a replication channel using the ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS option of the CHANGE REPLICATION SOURCE TO statement, sql_replica_skip_counter or sql_slave_skip_counter is available. For more information, see Section 2.7.3, “Skipping Transactions”.

Ignoring servers.  The IGNORE_SERVER_IDS option of the CHANGE REPLICATION SOURCE TO | 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 REPLICA 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 mysql_upgrade.  Prior to MySQL 8.0.16, when the server is running with global transaction identifiers (GTIDs) enabled (gtid_mode=ON), do not enable binary logging by mysql_upgrade (the --write-binlog option). As of MySQL 8.0.16, the server performs the entire MySQL upgrade procedure, but disables binary logging during the upgrade, so there is no issue.