A safe MySQL upgrade that wasn't so safe
Summary
The post recounts a MySQL upgrade that introduced data integrity issues in a replicated setup. It explains how adding an AUTO_INCREMENT column during migration can cause ID ordering differences between source and replica, and how different binary log formats (STATEMENT vs ROW) under MIXED mode can propagate those mismatches to related tables. The piece emphasizes thorough testing and careful handling of replication behavior during upgrades to avoid cascading data reference errors.