Redis

Redis keeps data in memory and typically answers in under a millisecond, which is why apps put it next to their main database. It is a key-value store whose values are real data structures: strings, hashes, lists, sets and sorted sets. This track starts from zero in redis-cli. You will store and expire keys, count with atomic increments and model objects with hashes. Then you will build the patterns that power real apps: a cache in front of a database, a rate limiter, a job queue, a leaderboard and live events with pub/sub.

Every example shows the exact replies redis-cli prints, so you always know what to expect.