What problem does it solve? Changing production database schemas without downtime or data loss is risky: a single bad migration can lock tables, rewrite millions of rows, or break running applications. This Skill provides proven patterns for writing safe, reversible migrations and planning zero-downtime schema changes. ## Core Features & Use Cases - Safety Checklists: Enforces rules like never adding NOT NULL without a default, using CREATE INDEX CONCURRENTLY, and separating schema from data migrations. - Multi-Tool Coverage: Includes concrete workflows and code examples for Prisma, Drizzle, Django, golang-migrate, and raw PostgreSQL. - Zero-Downtime Patterns: Guides the expand-contract pattern for renaming or removing columns without breaking deployed applications. - Use Case: You need to rename a heavily used column in a production PostgreSQL table. The Skill walks you through adding the new column, backfilling data in batches, deploying dual-write application code, and dropping the old column in a later migration. ## Quick Start Ask the assistant to help you write a safe migration to add a non-nullable column with an index to your production users table.
