Database Patterns

This is your reference when you're writing Alembic migrations or designing schemas and don't want to break production. It covers the stuff that bites you: two-phase NOT NULL additions, concurrent index creation, proper downgrade implementations, and when to denormalize. The zero-downtime migration patterns using expand-contract are solid, and the anti-patterns section actually calls out real footguns like running autogenerate in production or modifying deployed migrations. Defaults to PostgreSQL with asyncpg, includes NoSQL patterns when you need them. The 12 rules split across migration mechanics, schema design, and versioning are all lazy-loaded, so it stays out of your way until you hit a migration file or schema pattern.