MySQL replication has been around forever, and yet… people still manage to set it up in ways that break at the worst possible moment. Even in 2025, you can get burned by tiny schema differences, missing primary keys, or one forgotten config flag. I’ve seen replicas drift so far out of sync they might as well live in a different universe.
This is a companion discussion topic for the original entry at https://percona.community/blog/2025/12/03/mysql-replication-best-practices-how-to-keep-your-replicas-sane-and-your-nights-quiet