Database Migrations

This covers the full lifecycle of database schema changes: safe column additions, concurrent index creation, zero-downtime renames using expand-contract, and batched data migrations that won't lock your tables. It includes patterns for PostgreSQL, MySQL, and five ORMs (Prisma, Drizzle, Kysely, Django, TypeORM, golang-migrate) with real migration file examples. The safety checklist alone is worth having open when you're about to add a NOT NULL column to a 50 million row table at 2pm on a Tuesday. Best for teams that have been bitten by a full table rewrite in production and want the playbook to never let it happen again.

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last updated: Jul 14, 2026

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Install

$ npx -y skills add affaan-m/everything-claude-code --skill database-migrations --agent claude-code

Installs into .claude/skills of the current project.

Files

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

Every change is a migration — never alter production databases manually
Migrations are forward-only in production — rollbacks use new forward migrations
Schema and data migrations are separate — never mix DDL and DML in one migration
Test migrations against production-sized data — a migration that works on 100 rows may lock on 10M
Migrations are immutable once deployed — never edit a migration that has run in production