Errant GTIDs Breaking Replication: How to Detect and Avoid Them

GTIDs were introduced to solve replication problems and improve database consistency. When, accidentally, transactions occur on a replica, this introduces GTIDs on that replica that don’t exist on the master. When, on a master failover, this replica becomes the new master, and the corresponding binlogs of the errant GTIDs are already purged, replication breaks on the replicas of this new master, because those missing GTIDs can’t be retrieved from the binlogs of this new master. This presentation will talk about GTIDs and how to detect errant GTIDs on a replica (before the corresponding binlogs are purged) and how to look at the corresponding transactions in the binlogs. I’ll give some examples of transactions that could happen on a replica that didn’t originate from a primary node, explain how this is possible and share some tips on how to avoid this. Basic understanding of MySQL database replication is assumed.