Glossary

Redis

Redis is an in-memory data store with string, hash, list, set, sorted set, and stream structures. Since all data lives in RAM, operations execute in microseconds. Most commonly used as a cache, queue broker, and pub/sub system.

Typical use cases

Caching — store the result of an expensive SQL query for N seconds
Sessions — fast session storage instead of a database
Queues — reliable broker for background jobs; workers read tasks via BRPOP or Streams
Rate limiting — atomic counter increment per time window
Pub/Sub — broadcast events between services in real time

Persistence

Redis stores data in memory but supports two disk-dump modes: RDB (snapshots) and AOF (log of all operations). Persistence is not critical for caching — for queues, enable AOF.