Redis Commands Cheat Sheet

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Redis data structures, commands, expiry, pub/sub, and common caching patterns

String Commands

SET & GET

Store and retrieve string values

SET key "value"          # set a key
SET key "value" EX 3600  # set with 1 hour TTL
GET key                   # get value
GETSET key "newval"       # get old, set new (atomic)
SETNX key "value"         # set only if not exists
MSET a 1 b 2 c 3          # set multiple keys
MGET a b c                # get multiple keys

Increment & Append

Modify numeric and string values atomically

INCR counter              # increment by 1
INCRBY counter 10         # increment by N
DECR counter              # decrement by 1
DECRBY counter 5          # decrement by N
APPEND key " more text"   # append to string

List Commands

Push & Pop

Add and remove elements from list ends

LPUSH mylist "a"          # push to left (head)
RPUSH mylist "b"          # push to right (tail)
LPOP mylist               # pop from left
RPOP mylist               # pop from right
BLPOP mylist 30           # blocking pop (wait up to 30s)

Query

Read list elements and length

LRANGE mylist 0 -1        # get all elements
LRANGE mylist 0 9         # get first 10
LLEN mylist               # length of list
LINDEX mylist 0           # element at index
LSET mylist 0 "newval"    # set element at index

Hash Commands

Set & Get Fields

Store and retrieve hash field values

HSET user:1 name "Alice" age 30
HGET user:1 name          # "Alice"
HMGET user:1 name age     # ["Alice", "30"]
HGETALL user:1            # all fields and values

Modify & Query

Update, delete, and inspect hash fields

HDEL user:1 age           # delete field
HEXISTS user:1 name       # 1 (exists)
HKEYS user:1              # ["name", "age"]
HVALS user:1              # ["Alice", "30"]
HLEN user:1               # number of fields
HINCRBY user:1 score 5    # increment numeric field

Set Commands

Add & Query

Add members and query set membership

SADD myset "a" "b" "c"    # add members
SMEMBERS myset            # all members
SISMEMBER myset "a"       # 1 (is member)
SCARD myset               # count members
SREM myset "b"            # remove member
SRANDMEMBER myset         # random member

Set Operations

Union, intersection, and difference of sets

SUNION set1 set2           # union
SINTER set1 set2           # intersection
SDIFF set1 set2            # difference (in set1 not set2)
SUNIONSTORE dest set1 set2 # store result in dest

Sorted Set Commands

ZADD & ZRANGE

Add scored members and query by rank

ZADD leaderboard 1000 "alice"
ZADD leaderboard 850 "bob" 920 "carol"
ZRANGE leaderboard 0 -1              # all by rank (ascending)
ZRANGE leaderboard 0 -1 WITHSCORES   # with scores
ZREVRANGE leaderboard 0 9            # top 10 (descending)
ZRANK leaderboard "alice"            # rank (0-indexed)
ZSCORE leaderboard "alice"           # score

Key Commands

TTL & Expiry

Set and check expiration on keys

EXPIRE key 3600           # expire in 3600 seconds
EXPIREAT key 1893456000   # expire at Unix timestamp
TTL key                   # seconds remaining (-1 = no TTL, -2 = gone)
PERSIST key               # remove expiry

Inspect & Delete

Check and manage keys

EXISTS key                # 1 if exists
DEL key1 key2             # delete keys
TYPE key                  # "string", "list", "hash", etc.
SCAN 0 MATCH user:* COUNT 100  # safe iteration (use instead of KEYS)

Pub/Sub

Publish & Subscribe

Message passing between clients

# Client 1 - subscribe
SUBSCRIBE channel1
PSUBSCRIBE news.*         # pattern subscribe

# Client 2 - publish
PUBLISH channel1 "message"

# Client 1 - unsubscribe
UNSUBSCRIBE channel1

Common Patterns

Session Storage

Store user sessions with automatic expiry

# Store session (Node.js with ioredis)
const sessionId = crypto.randomUUID();
const sessionData = JSON.stringify({ userId: 123, role: "admin" });

await redis.set(`session:${sessionId}`, sessionData, "EX", 86400);
// EX 86400 = expire in 24 hours

# Read session
const raw = await redis.get(`session:${sessionId}`);
const session = raw ? JSON.parse(raw) : null;

# Refresh session on activity
await redis.expire(`session:${sessionId}`, 86400);

# Delete on logout
await redis.del(`session:${sessionId}`);

Rate Limiting with INCR + EXPIRE

Simple sliding window rate limiter

# Rate limit: 100 requests per minute per IP
async function isRateLimited(ip: string): Promise<boolean> {
  const key = `rate:${ip}:${Math.floor(Date.now() / 60000)}`;

  const count = await redis.incr(key);
  if (count === 1) {
    await redis.expire(key, 60); // set TTL only on first increment
  }

  return count > 100; // limit: 100 req/min
}

# Usage
if (await isRateLimited(clientIp)) {
  return res.status(429).json({ error: "Too many requests" });
}

Leaderboard with Sorted Sets

Real-time leaderboard using ZADD and ZREVRANGE

# Update score
await redis.zadd("leaderboard", score, userId);

# Get top 10 with scores
const top10 = await redis.zrevrange("leaderboard", 0, 9, "WITHSCORES");
// Returns flat array: [userId, score, userId, score, ...]

# Get rank of a user (0 = top)
const rank = await redis.zrevrank("leaderboard", userId);

# Get score of a user
const score = await redis.zscore("leaderboard", userId);

# Get users in a score range
const players = await redis.zrangebyscore("leaderboard", 900, 1000);

Tips & Best Practices

Always set a TTL on cached keys — never cache without an expiry to prevent unbounded memory growth

Use SCAN instead of KEYS pattern in production — KEYS blocks the server

Use namespaced key prefixes (user:123:session) to organize and avoid collisions

Use pipelining (batch commands) for multiple operations to reduce round-trip latency

Monitor memory usage with INFO memory and set maxmemory-policy allkeys-lru for cache use cases

Additional Resources

Redis Commands Reference

Full Redis command documentation

Redis Data Types

In-depth guide to Redis data structures

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