Posted On: Mar 25, 2019
A Global Transaction Identifier (GTID) is a unique identifier created and associated with each transaction committed to a MySQL database. GTIDs are now supported by Amazon Aurora with MySQL 5.7 compatibility, allowing simpler and less error-prone database replication.
Traditional MySQL replication is based on relative coordinates, with each replica keeping track of its position with respect to its current master's binary log files. GTID is based on absolute coordinates, with each transaction having a unique identifier, and each MySQL database server keeping track of which transactions it has already executed.
This provides complete consistency when using binlog replication between an Aurora database and an external MySQL database. Your replication won’t miss transactions or generate conflicts, even after failover or downtime. (Note that replication within an Aurora cluster doesn't use binlog files, so the GTID feature doesn't apply.)