Where state lives. From relational foundations to modern distributed stores — choosing, tuning, and understanding the systems that hold your data.
Explore Topics
Joins, subqueries, window functions, CTEs — the query patterns that turn tables into answers.
Normal forms, denormalization trade-offs, and when to break the rules for performance.
B-trees, hash indexes, covering indexes — how databases find your data and what EXPLAIN is telling you.
MongoDB, Redis, Neo4j — when relational isn't the right fit and what you give up by leaving it.
Read committed, repeatable read, serializable — the spectrum of correctness guarantees and their costs.
Evolving schemas in production without locking tables or breaking running applications.