Redis ist nicht nur ein Key-Value-Store. Cache, Sessions, Rate Limiting, Pub/Sub, Leaderboards – eine vielseitige In-Memory-Datenbank.

Cache-Pattern¶

import redis r = redis.Redis() def get_user(user_id):

Check cache¶

cached = r.get(f”user:{user_id}”) if cached: return json.loads(cached)

Cache miss – fetch from DB¶

user = db.users.find_one(user_id) r.setex(f”user:{user_id}”, 3600, json.dumps(user)) # TTL 1h return user

Rate Limiter¶

def rate_limit(key, limit=100, window=60): pipe = r.pipeline() now = time.time() pipe.zremrangebyscore(key, 0, now - window) pipe.zadd(key, {str(now): now}) pipe.zcard(key) pipe.expire(key, window) _, _, count, _ = pipe.execute() return count <= limit

Pub/Sub¶

Publisher¶

r.publish(‘notifications’, json.dumps({‘user’: 123, ‘msg’: ‘Hello’}))

Subscriber¶

pubsub = r.pubsub() pubsub.subscribe(‘notifications’) for message in pubsub.listen(): if message[‘type’] == ‘message’: handle(json.loads(message[‘data’]))

Wichtigste Erkenntnis¶

Cache mit TTL, Sorted Set fuer Rate Limiting, Pub/Sub fuer Echtzeit. Redis = Schweizer Taschenmesser.