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.
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.
Temporary tables.
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
autocommit=1
.
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 16.1.3.4, “Setting Up Replication Using GTIDs”.
Skipping transactions.
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 16.1.7.3, “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.
GTID mode and mysql_upgrade.
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).