Everything we have written on Database.
How database indexes actually work, how to read a query plan, composite index ordering, and the costs nobody warns app developers about.
Most projects do not need a fancy database, just one boring, reliable one that does everything well. Here is the honest case for Postgres.
How to use Redis caching without shooting yourself in the foot: real patterns for read-through caches, invalidation, TTLs, and the stampede problem.
