What does GTID refer to in MySQL?

In MySQL, GTID (Global Transaction Identifier) is a type of global transaction identifier that is automatically generated and assigned by the MySQL server. It is used in distributed environments to track and recover transactions. Each GTID consists of three parts: the GTID domain identifier, server UUID, and transaction ID.

GTID serves to ensure data consistency and fault recovery in master-slave replication. When a transaction is committed on the master server, it is assigned a unique GTID. The replication slave server tracks and records the GTID of each replicated transaction so that it can accurately locate and recover to the specified transaction when there is a master-slave switch, fault recovery, or replication delay.

Using GTID simplifies the configuration and management of master-slave replication, while also providing more reliable data replication. It helps prevent data conflicts and duplicate replication during the process, and makes it easier to perform failover and master-slave switching.