database-migrations

npx skills add mturac/everything-openai-codex --skill database-migrations --agent codex

Same command for any agent — swap --agent for claude-code, cursor, copilot.

# Database Migration Patterns Safe, reversible database schema changes for production systems. ## When to Activate - Creating or altering database tables - Adding/removing columns or indexes - Running data migrations (backfill, transform) - Planning zero-downtime schema changes - Setting up migration tooling for a new project ## Core Principles 1. **Every change is a migration** — never alter production databases manually 2. **Migrations are forward-only in production** — rollbacks use new forward migrations 3. **Schema and data migrations are separate** — never mix DDL and DML in one migration 4. **Test migrations against production-sized data** — a migration that works on 100 rows may lock on 10M 5. **Migrations are immutable once deployed** — never edit a migration that has run in production ## Migration Safety Checklist Before applying any migration: - [ ] Migration has both UP and DOWN (or is explicitly marked irreversible) - [ ] No full table locks on large tables (use concurrent operations) - [ ] New columns have defaults or are nullable (never add NOT NULL without default) - [ ] Indexes created concurrently (not inline with CREATE TABLE for existing tables) - [ ] Data backf

Create migration from schema changes
npx prisma migrate dev --name add_user_avatar
Apply pending migrations in production
npx prisma migrate deploy
Reset database (dev only)
npx prisma migrate reset
Generate client after schema changes
npx prisma generate
Create empty migration, then edit the SQL manually
npx prisma migrate dev --create-only --name add_email_index