tech

Redis

In-Memory-Datenspeicher für Caching, Sessions und Echtzeit-Analytik - blitzschnelle Key-Value-Operationen

TL;DR

Was: In-Memory-Datenstrukturspeicher - Cache, Datenbank, Message Broker.

Warum: Ultra-schnelle Lese-/Schreibvorgänge, einfache API, vielseitige Datenstrukturen.

Quick Start

Installieren:

# macOS
brew install redis
brew services start redis

# Ubuntu/Debian
sudo apt install redis-server
sudo systemctl start redis

# Docker
docker run -d --name redis -p 6379:6379 redis:7

Verbinden:

redis-cli

# Remote
redis-cli -h hostname -p 6379 -a password

Grundoperationen:

# String
SET name "Alice"
GET name

# With expiration (seconds)
SET session "abc123" EX 3600

# Check TTL
TTL session

# Delete
DEL name

Cheatsheet

Befehl	Beschreibung
`SET key value`	String-Wert setzen
`GET key`	String-Wert abrufen
`DEL key`	Schlüssel löschen
`EXISTS key`	Prüfen ob Schlüssel existiert
`EXPIRE key seconds`	Ablaufzeit setzen
`TTL key`	Verbleibende TTL abrufen
`KEYS pattern`	Schlüssel finden (SCAN in Prod verwenden)
`FLUSHDB`	Alle Schlüssel in DB löschen
`INFO`	Serverinformationen

Datenstrukturen:

# List
LPUSH mylist "a" "b" "c"
LRANGE mylist 0 -1

# Set
SADD myset "a" "b" "c"
SMEMBERS myset

# Hash
HSET user:1 name "Alice" age 30
HGETALL user:1

# Sorted Set
ZADD leaderboard 100 "player1" 200 "player2"
ZRANGE leaderboard 0 -1 WITHSCORES

Gotchas

Connection refused

# Check if Redis is running
redis-cli ping  # Should return PONG

# Check service status
sudo systemctl status redis

# Check if binding to localhost only
# In redis.conf: bind 127.0.0.1

NOAUTH Authentication required

# Connect with password
redis-cli -a yourpassword

# Or after connecting
AUTH yourpassword

# Set password in redis.conf
requirepass yourpassword

Speicherprobleme

# Check memory usage
redis-cli INFO memory

# Set max memory
# redis.conf: maxmemory 256mb
# redis.conf: maxmemory-policy allkeys-lru

KEYS nicht in Produktion verwenden

# KEYS blocks the server - use SCAN instead
SCAN 0 MATCH "user:*" COUNT 100