Skill: Database Migration

Description

Handles safe database schema changes and data migrations.

When to Use

• •Adding/modifying database tables or columns
• •Changing relationships between entities
• •Data transformations

Instructions

Migration Rules

1. •Always reversible — every migration needs an up and down
2. •One change per migration — don't bundle unrelated schema changes
3. •Test on dev first — never run untested migrations in production
4. •Backup before production — always have a rollback plan
5. •No data loss — add columns as nullable first, then backfill

Drizzle Workflow

# Generate migration from schema changes
npx drizzle-kit generate

# Review generated SQL in drizzle/ folder
# Apply migration
npx drizzle-kit push

# Or use migrate for production
npx drizzle-kit migrate

Naming Convention

YYYYMMDD_HHMMSS_description.sql Example: 20260212_143000_add_user_roles.sql

Dangerous Operations Checklist

• • Column rename → Create new, copy data, drop old (3-step)
• • Column type change → Verify data compatibility first
• • Drop table → Confirm no foreign key references
• • Add NOT NULL → Set default or backfill first