Redis Explained: The In-Memory Store That Makes Everything Faster
Introduction Redis is an in-memory data store: it keeps data in RAM instead of on disk, which makes it roughly a hundred times faster than a disk database for simple operations — but also means it is not where your permanent data should live alone. Redis is the accelerator you bolt onto a real database, and it powers caching, sessions, leaderboards, and queues across the modern web. Caching: the job Redis is famous for The most common Redis job is caching: storing the result of an expensive database query so the next request doesn't repeat it. User requests homepage → Check Redis for "homepage:en" → Found? Return it instantly (milliseconds) → Not found? Query Postgres, store the result in Redis with a 60-second expiry, return it Expiry is the key idea: cached data gets a time-to-live (TTL), after which Redis deletes it and the next request refreshes it from the real database. Stale-for-a-minute data is a fine trade for a homepage that loads instantly, and T...