Redis Tutorial

In-memory data with Redis — strings, hashes, lists, sets, and caching patterns.

1 min read 127 words Updated Mar 13, 2026

Redis is an in-memory data store used for caching, sessions, queues, and real-time counters.

Strings and expiry

SET views:home 0
INCR views:home
EXPIRE views:home 3600      # cache for 1 hour
GET views:home

Hashes

HSET user:1 name "Ada" plan "pro"
HGET user:1 name
HGETALL user:1

Lists and sets

LPUSH tasks "send-email"
RPOP tasks                 # pop from the right

SADD online user:1 user:2
SCARD online              # count of online users

Caching pattern

import redis, json

r = redis.Redis()

def get_user(uid):
    key = f"user:{uid}"
    cached = r.get(key)
    if cached:
        return json.loads(cached)
    user = db_query(uid)            # expensive
    r.set(key, json.dumps(user), ex=300)
    return user

Structure	Best for
String	counters, cache values
Hash	object fields
List	queues, timelines
Set	unique membership, tags

Set a sensible EX (expiry) on caches so stale data eventually refreshes.