/postgres-database-migration

Tiger Data · timescale/pg-aiguide
1.9kUse this skill for planning, testing, and safely executing PostgreSQL schema migrations — especially when working with production data or shared databases.
**Trigger when user asks to:**
- Test a schema migration before applying it to production
- Add, remove, or rename columns safely on a live table
- Change a column's data type without downtime
- Add or drop indexes, constraints, or foreign keys on large tables
- Understand which ALTER TABLE operations lock the table
- Roll back a failed migration
- Plan a zero-downtime migration strategy
- Fork a database to test a migration safely
**Keywords:** migration, schema change, ALTER TABLE, add column, drop column, rename column, change type, zero downtime, lock, AccessExclusiveLock, concurrent index, forking, rollback, backfill, deploy
Covers: lock-level reference for every common DDL operation, safe migration patterns, fork-based testing, zero-downtime column changes, index creation, constraint addition, backfill strategies, pre/post-migration validation, and rollback planning.