The Complete Guide to Redis¶

Redis is an in-memory data store. Ultra fast. Indispensable.

Basic Operations¶

SET key “value” EX 3600 # with expiration GET key DEL key EXISTS key TTL key

Data Structures¶

Strings¶

INCR counter INCRBY counter 5

Hash¶

HSET user:1 name “Jan” email “[email protected]” HGETALL user:1

List¶

LPUSH queue “task1” RPOP queue

Set¶

SADD tags “python” “devops” SMEMBERS tags

Sorted Set¶

ZADD leaderboard 100 “player1” 200 “player2” ZREVRANGE leaderboard 0 9 WITHSCORES

Use Cases¶

• Cache — the most common, SET/GET with TTL
• Sessions — user session storage
• Rate limiting — INCR + EXPIRE
• Queue — LPUSH + BRPOP
• Pub/Sub — real-time messaging
• Leaderboard — Sorted Sets

Persistence¶

• RDB — point-in-time snapshot
• AOF — append-only file (more durable)
• RDB + AOF — recommended for production

Cluster¶

Redis Cluster for horizontal scaling. Automatic sharding and failover.

Rule¶

Redis is a cache, not a primary database (with exceptions). Always have a fallback to primary storage.