Database Migrations

This is a comprehensive reference for production database migrations across Postgres, MySQL, and popular ORMs like Prisma, Drizzle, Kysely, Django, and TypeORM. It covers the critical stuff that bites you in production: zero-downtime column renames using expand-contract patterns, concurrent index creation to avoid table locks, batched updates for large tables, and the absolute rule that you never edit a migration after it runs. The safety checklist alone (nullable columns, separate schema and data migrations, testing against production-sized data) is worth having open during code review. Especially useful if you're moving from "just run ALTER TABLE" to proper migration discipline, or if you've been burned by a migration that worked fine in dev but locked your production table for twenty minutes.

skills.sh installs: 6.4K
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last updated: Aug 21, 2026

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Install

$ npx -y skills add affaan-m/ecc --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