Database Expert

This is a solid reference for PostgreSQL, MongoDB, and Redis fundamentals. It covers the essentials: schema design patterns, query optimization with EXPLAIN ANALYZE, indexing strategies including partial and covering indexes, and Redis caching patterns like cache-aside and distributed locking. The PostgreSQL section is the strongest with practical examples of CTEs, window functions, and triggers. Use this when you need quick syntax for common database operations or want to compare approaches across different database types. It won't make you a DBA, but it handles the 80% of database work that comes up in typical application development without having to context switch to documentation.