database-migration-skill

What I do

I help you manage database schema changes safely and repeatably:

1. Schema Evolution: Design schemas that change safely over time
2. Prisma Migrations: TypeScript/Node.js migration workflow
3. Alembic Migrations: Python/SQLAlchemy migration workflow
4. Django Migrations: Django ORM migration workflow
5. Rollback Strategies: Safe rollback planning and execution
6. Zero-Downtime Migrations: Techniques for production-safe schema changes
7. Seed Data: Manage test and development seed data
8. Migration Testing: Verify migrations work correctly before production

When to use me

Use this skill when:

• Creating or modifying database schema
• Setting up a migration system for a new project
• Writing reversible migrations
• Planning zero-downtime production migrations
• Managing seed data for development/testing
• Debugging failed migrations
• Setting up migration CI checks
• Converting between migration tools

Related Skills

• performance-optimization-skill: Handles runtime query profiling and optimization. This skill handles schema lifecycle. Index optimization can overlap — this skill handles index creation in migrations, performance skill handles query analysis.
• python-backend-skill: FastAPI/Django/Flask project patterns that use these migration tools.
• docker-containerization-skill: Database containers in compose configurations.

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Step 1: Migration Principles

Rules for Safe Migrations

1. Never modify an existing migration that has been applied
2. Always make migrations reversible (with rare exceptions)
3. Test migrations against production-like data before deploying
4. Use separate migrations for additive and destructive changes
5. Prefer additive changes — add new columns/tables before removing old ones

Migration Categories

Type	Risk	Reversibility	Example
Additive (create table, add column)	Low	Easy	Add phone column to users
Add constraint	Medium	Moderate	Add NOT NULL, foreign key
Add index	Low	Easy	Add index on users.email
Rename column/table	Medium	Hard	Rename name to full_name
Remove column/table	High	Hard (data loss)	Drop legacy_field
Change column type	High	Hard	Change int to bigint
Data migration	Medium	Moderate	Backfill new column from old data