Database Patterns

This is a reference guide for PostgreSQL and Redis patterns you'd actually use in production. It covers the practical stuff: when to use JSONB versus proper columns, how to set up composite indexes that follow the leftmost prefix rule, cache-aside with stampede prevention, and TTL strategies for different data types. The code examples are concrete, like using NUMERIC(19,4) for money instead of floats, or caching null results to prevent penetration attacks. It takes opinionated stances (UUIDs over integers, no backward compatibility) which saves you from bikeshedding. Good for anyone building systems where caching strategy matters and you need to know whether a GIN index or expression index makes more sense for your JSONB queries.