How Redis Uses Key-Value Pairs and Hashing to Cache Data Per User

Redis is an in-memory key-value store that sits between an application's backend and its database, serving frequently requested data faster than a traditional database query. Rather than storing data by user identity inherently, Redis relies on the backend to construct unique, structured keys — such as 'user:123:cart' — to keep each user's cached data separate. When requests include multiple filters like status or page number, those parameters are incorporated into the cache key, or compressed into a fixed-length hash using functions like MD5 or xxHash, to ensure consistent key generation. This means the backend can regenerate the same hash from an identical request and retrieve the cached result without hitting the database again. Static UI assets like HTML and CSS are not stored in Redis but are instead handled by a separate system called a Content Delivery Network (CDN).