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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 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 using 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. This problem can also occur in at least two other cases, listed here:
When the master and the slave use different storage engines for their respective versions of the same table, where one storage engine is transactional and the other is not.
When both the master and the slave use a nontransactional engine, but use different
binary logging formats (for example, when the master has binlog_format=ROW
and the slave has binlog_format=STATEMENT
).
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
is not safe for statement-based replication. When using
row-based replication, this statement is actually logged as two separate events—one for the creation of the
table, and another for the insertion of rows from the source table into the new table just created. When this
statement is executed within a transaction, it is possible in some cases for these two events to receive the
same transaction identifier, which means that the transaction containing the inserts is skipped by the slave.
Therefore, CREATE TABLE ... SELECT
is not supported when using GTID-based
replication.
Temporary tables. CREATE TEMPORARY
TABLE
and DROP TEMPORARY TABLE
statements are not supported inside transactions when using
GTIDs (that is, when the server was started with the --enforce-gtid-consistency
option). It is possible to use use these statements
with GTIDs enabled, but only outside of any transaction, and only with autocommit=1
.
Preventing execution of unsupported statements. In order 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.
For information about other required startup options when enabling GTIDs, see Section 16.1.3.2, "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 master's gtid_executed
variable instead; see Injecting empty transactions, for more
information.
GTID mode and mysqldump. In MySQL 5.6.9 and later, 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.
Prior to MySQL 5.6.9, mysqldump did not record global transaction IDs, and it was necessary to use the binary log and mysqlbinlog to restore GTIDs. (Bug #14797808, Bug #14832472)
GTID mode and mysql_upgrade.
Prior to MySQL 5.6.7, mysql_upgrade could not connect to a MySQL Server that was
running with --gtid-mode=ON
unless mysql_upgrade was run with --write-binlog=OFF
. (Otherwise, mysqld had to be restarted with --gtid-mode=OFF
before running mysql_upgrade,
then restarted with --gtid_mode=ON
afterwards.) This is not an issue in MySQL 5.6.7
and later, where mysql_upgrade
runs with --write-binlog=OFF
by default. (Bug #13833710) However, it is not
recommended to do so, since mysql_upgrade can make changes to system tables that use the
MyISAM
storage engine, which is nontransactional.