Redis Essentials

Session storage: Fast read/write for user sessions
Rate limiting: Track request counts with INCR and EXPIRE
Leaderboards: Sorted sets for real-time rankings
Pub/Sub: Real-time messaging between services
Queue: Lists as simple job queues

Redis is an in-memory data structure store used as a cache, database, and message broker.

Core Data Types

SET user:1:name "Alice"
GET user:1:name          → "Alice"
SET counter 0
INCR counter             → 1

HSET user:1 name "Alice" age "30" city "NYC"
HGET user:1 name         → "Alice"
HGETALL user:1           → name, Alice, age, 30, city, NYC

LPUSH queue "task1"
LPUSH queue "task2"
RPOP queue               → "task1"

SADD tags:post1 "redis" "caching" "database"
SMEMBERS tags:post1      → redis, caching, database
SISMEMBER tags:post1 "redis"  → 1 (true)

ZADD leaderboard 100 "alice" 85 "bob" 92 "charlie"
ZREVRANGE leaderboard 0 2     → alice, charlie, bob

SET session:abc123 "user_data" EX 3600   # Expires in 1 hour
TTL session:abc123                        # Seconds remaining