What happened
Alert fired for PostgreSQL High Rollback Rate on pgdb-orders-instance-3. Rollback ratio reached ~2.2%, with peaks up to 4.3%.
Root cause: chronic schema drift. Missing alert_outcome column and canvas_doc_state table on orders-db-cluster.
Key evidence
- 137,639 combined schema errors during incident window.
- Migration PR identified: alert_outcome_column.sql (PR #27326), merged to main but never applied to the cluster.
Suggested fix
Change run-db-migrations default from false to true in deploy-orders.yml to ensure migrations run by default on orders-db-cluster deployments.

