Redis — Advanced

Redis Cluster

python

from redis.cluster import RedisCluster

# Connect to Redis Cluster (shards data across nodes automatically)
rc = RedisCluster(
    host="redis-cluster.example.com",
    port=6379,
    password="secret",
    decode_responses=True,
    skip_full_coverage_check=True
)

# Hash tags — force keys to same shard for multi-key operations
# Keys with {same-tag} hash the same way
rc.set("{user:123}:session", "data1")
rc.set("{user:123}:preferences", "data2")
rc.set("{user:123}:cart", "data3")
# All on same shard → MGET, pipeline, and transactions work

# Operations that DON'T work across shards:
# - MSET/MGET with different hash slots
# - Transactions touching multiple shards
# - SUNION/SINTER across shards

KeyDB and Dragonfly (Redis Alternatives)

bash

# KeyDB — multi-threaded Redis fork, 5-10x more throughput
# Drop-in replacement, same protocol
docker run -p 6379:6379 eqalpha/keydb
# Same client code, same commands

# Dragonfly — modern Redis replacement, uses all CPU cores
docker run -p 6379:6379 docker.dragonflydb.io/dragonflydb/dragonfly
# 25x more throughput than Redis on same hardware
# Compatible with Redis clients and protocol

Production Configuration

ini

# redis.conf — production hardening

# Memory
maxmemory 8gb
maxmemory-policy allkeys-lru   # Evict LRU keys when full (for cache)
# Options: allkeys-lru, allkeys-lfu, volatile-lru, volatile-ttl, noeviction

# Persistence
appendonly yes                  # AOF for durability
appendfsync everysec            # Sync every second (balanced)
save 900 1                      # RDB snapshot: 1 change in 900s
save 300 10
save 60 10000
# Both AOF + RDB = best recovery options

# Security
requirepass "strong-random-password-here"
rename-command FLUSHALL ""     # Disable dangerous commands
rename-command FLUSHDB ""
rename-command CONFIG "CONFIG_RENAMED_XXXX"

# Network
bind 10.0.0.1 127.0.0.1        # Only listen on internal interfaces
protected-mode yes
tcp-backlog 511

# Performance
tcp-keepalive 300
hz 10                           # Background tasks frequency
lazyfree-lazy-eviction yes      # Non-blocking eviction
lazyfree-lazy-expire yes        # Non-blocking TTL expiry
io-threads 4                    # (Redis 6+) Parallel I/O

Redis Cheatsheet

bash

# ── SERVER ────────────────────────────────────────────────
redis-cli INFO server | grep version
redis-cli INFO memory | grep used_memory_human
redis-cli INFO keyspace
redis-cli DEBUG SLEEP 0   # Test connectivity
redis-cli MONITOR          # Watch all commands (debug only)
redis-cli SLOWLOG GET 10   # Last 10 slow commands

# ── KEY MANAGEMENT ────────────────────────────────────────
KEYS pattern        # Dangerous in prod! Blocks
SCAN 0 MATCH user:* COUNT 100  # Safe iterative
TYPE key            # string/list/set/zset/hash/stream
TTL key             # Seconds remaining (-1=no expiry, -2=gone)
PERSIST key         # Remove TTL
RENAME key newkey
OBJECT ENCODING key # See how Redis stores internally

# ── DEBUGGING ─────────────────────────────────────────────
OBJECT IDLETIME key  # Seconds since last access
DEBUG OBJECT key     # Memory usage
MEMORY USAGE key     # Bytes used by key
OBJECT FREQ key      # Access frequency (LFU policy)
redis-cli --latency  # Measure network latency
redis-cli --stat     # Live server statistics