This section explains transaction-based replication using global transaction identifiers (GTIDs). When using GTIDs, each transaction can be identified and tracked as it is committed on the originating server and applied by any slaves; this means that it is not necessary when using GTIDs to refer to log files or positions within those files when starting a new slave or failing over to a new master, which greatly simplifies these tasks. Because GTID-based replication is completely transaction-based, it is simple to determine whether masters and slaves are consistent; as long as all transactions committed on a master are also committed on a slave, consistency between the two is guaranteed. You can use either statement-based or row-based replication with GTIDs (see Section 17.2.1, “Replication Formats”); however, for best results, we recommend that you use the row-based format.

GTIDs are always preserved between master and slave. This means that you can always determine the source for any transaction applied on any slave by examining its binary log. In addition, once a transaction with a given GTID is committed on a given server, any subsequent transaction having the same GTID is ignored by that server. Thus, a transaction committed on the master can be applied no more than once on the slave, which helps to guarantee consistency.

This section discusses the following topics:

For information about MySQL Server options and variables relating to GTID-based replication, see Section 17.1.6.5, “Global Transaction ID Options and Variables”. See also Section 12.18, “Functions Used with Global Transaction Identifiers (GTIDs)”, which describes SQL functions supported by MySQL 8.0 for use with GTIDs.