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 replicas; this means that it is not necessary when using GTIDs to refer to log files or positions within those files when starting a new replica or failing over to a new source, which greatly simplifies these tasks. Because GTID-based replication is completely transaction-based, it is simple to determine whether sources and replicas are consistent; as long as all transactions committed on a source are also committed on a replica, consistency between the two is guaranteed. You can use either statement-based or row-based replication with GTIDs (see Section 5.1, “Replication Formats”); however, for best results, we recommend that you use the row-based format.
GTIDs are always preserved between source and replica. This means that you can always determine the source for any transaction applied on any replica 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 source can be applied no more than once on the replica, which helps to guarantee consistency.
This section discusses the following topics:
How GTIDs are defined and created, and how they are represented in a MySQL server (see Section 2.3.1, “GTID Format and Storage”).
The life cycle of a GTID (see Section 2.3.2, “GTID Life Cycle”).
The auto-positioning function for synchronizing a replica and source that use GTIDs (see Section 2.3.3, “GTID Auto-Positioning”).
A general procedure for setting up and starting GTID-based replication (see Section 2.3.4, “Setting Up Replication Using GTIDs”).
Suggested methods for provisioning new replication servers when using GTIDs (see Section 2.3.5, “Using GTIDs for Failover and Scaleout”).
Restrictions and limitations that you should be aware of when using GTID-based replication (see Section 2.3.6, “Restrictions on Replication with GTIDs”).
Stored functions that you can use to work with GTIDs (see Section 2.3.7, “Stored Function Examples to Manipulate GTIDs”).
For information about MySQL Server options and variables relating to GTID-based replication, see Section 2.6.5, “Global Transaction ID System Variables”. See also Functions Used with Global Transaction Identifiers (GTIDs), which describes SQL functions supported by MySQL 8.0 for use with GTIDs.