REDIS QUICK REFERENCE
Strings, lists, sets, hashes, pub/sub, persistence
Connecting
CLI
redis-cli
redis-cli -h 127.0.0.1 -p 6379
redis-cli -a password -n 2
redis-cli --tls -u rediss://user:pass@host:6380
Driver Connection (Python)
import redis
r = redis.Redis(host='localhost', port=6379, db=0)
r.set('key', 'value')
print(r.get('key'))
Server Info
PING -- returns PONG
INFO server -- server details
INFO memory -- memory usage
DBSIZE -- number of keys in current db
Strings
Basic Operations
SET name "Alice"
GET name
SET counter 100
MSET a 1 b 2 c 3
MGET a b c
Numeric Operations
INCR counter -- 101
INCRBY counter 10 -- 111
DECR counter -- 110
DECRBY counter 5 -- 105
INCRBYFLOAT price 2.5
String Commands
| SET key val | Set string value |
| GET key | Get string value |
| SETNX key val | Set only if key does not exist |
| SETEX key sec val | Set with expiry in seconds |
| APPEND key val | Append to existing value |
| STRLEN key | Length of string value |
Lists
List Operations
LPUSH queue "first"
RPUSH queue "last"
LRANGE queue 0 -1 -- all elements
LPOP queue
RPOP queue
List Commands
| LPUSH / RPUSH | Push to left / right of list |
| LPOP / RPOP | Pop from left / right |
| LRANGE key start stop | Get range of elements |
| LLEN key | Length of list |
| LINDEX key idx | Element at index |
| LREM key count val | Remove count occurrences of val |
| BLPOP key timeout | Blocking pop (for queues) |
Sets & Sorted Sets
Set Operations
SADD tags "python" "redis" "docker"
SMEMBERS tags
SISMEMBER tags "python" -- 1 (true)
SREM tags "docker"
SCARD tags -- count
Set Math
SUNION set1 set2 -- union
SINTER set1 set2 -- intersection
SDIFF set1 set2 -- difference
Sorted Set Operations
ZADD leaderboard 100 "Alice" 85 "Bob"
ZRANGE leaderboard 0 -1 WITHSCORES
ZREVRANGE leaderboard 0 2
ZSCORE leaderboard "Alice"
ZRANK leaderboard "Alice" -- 0-based rank
Sorted Set Commands
| ZADD key score member | Add member with score |
| ZRANGE key start stop | Range by rank (low to high) |
| ZREVRANGE key start stop | Range by rank (high to low) |
| ZINCRBY key incr member | Increment member score |
| ZRANGEBYSCORE key min max | Range by score value |
| ZCARD key | Number of members |
Hashes
Hash Operations
HSET user:1 name "Alice" age 30
HGET user:1 name
HGETALL user:1
HMSET user:2 name "Bob" age 25
HMGET user:1 name age
Hash Commands
| HSET key field val | Set hash field |
| HGET key field | Get hash field |
| HGETALL key | Get all fields and values |
| HDEL key field | Delete hash field |
| HEXISTS key field | Check field existence |
| HINCRBY key field n | Increment field value |
| HKEYS key | All field names |
| HLEN key | Number of fields |
Keys & Expiry
Key Commands
| KEYS pattern | Find keys matching pattern (slow) |
| SCAN cursor MATCH pat | Iterate keys incrementally (safe) |
| EXISTS key | Check if key exists |
| DEL key | Delete key |
| TYPE key | Get key's data type |
| RENAME key newkey | Rename a key |
Expiry Commands
EXPIRE key 3600 -- expire in 1 hour
PEXPIRE key 5000 -- expire in 5000 ms
TTL key -- seconds until expiry
PTTL key -- ms until expiry
PERSIST key -- remove expiry
Key Patterns
SET session:abc123 "data" EX 1800
-- EX = seconds, PX = milliseconds
-- NX = only if not exists
-- XX = only if exists
SET lock:order42 "owner" NX EX 10
Pub/Sub
Basic Pub/Sub
-- Subscriber (terminal 1)
SUBSCRIBE news alerts
-- Publisher (terminal 2)
PUBLISH news "Breaking: Redis 8 released"
Pattern Subscribe
PSUBSCRIBE news.*
-- matches news.tech, news.sports, etc.
Pub/Sub Commands
| SUBSCRIBE channel | Listen for messages on channel |
| PUBLISH channel msg | Send message to channel |
| PSUBSCRIBE pattern | Subscribe to pattern |
| UNSUBSCRIBE channel | Stop listening |
| PUBSUB CHANNELS | List active channels |
Transactions
MULTI / EXEC
MULTI
SET balance:1 900
SET balance:2 1100
EXEC -- executes atomically
Optimistic Locking
WATCH balance:1
val = GET balance:1 -- read current
MULTI
SET balance:1 (val - 100)
EXEC
-- EXEC returns nil if balance:1 changed
Transaction Commands
| MULTI | Start transaction block |
| EXEC | Execute queued commands |
| DISCARD | Discard queued commands |
| WATCH key | Watch key for changes (optimistic lock) |
| UNWATCH | Forget all watched keys |
Persistence
RDB Snapshots
SAVE -- synchronous snapshot
BGSAVE -- background snapshot
LASTSAVE -- timestamp of last save
AOF (Append Only File)
| appendonly yes | Enable AOF in redis.conf |
| appendfsync always | Fsync every write (safest, slowest) |
| appendfsync everysec | Fsync once per second (recommended) |
| appendfsync no | Let OS decide (fastest, riskiest) |
Persistence Commands
CONFIG GET save
CONFIG SET save "900 1 300 10"
-- snapshot if 1 change in 900s or 10 in 300s
BGREWRITEAOF -- rewrite AOF in background
Common Patterns
Distributed Lock
SET lock:resource "owner-id" NX EX 30
-- NX = acquire only if not held
-- EX 30 = auto-release after 30s
DEL lock:resource -- explicit release
Rate Limiter
key = "rate:user:42"
INCR key
EXPIRE key 60 -- 60-second window
-- reject if GET key > max_requests
Caching Pattern
val = GET "cache:user:1"
if val is nil:
val = fetch_from_db(1)
SET "cache:user:1" val EX 300
Session Storage
HSET sess:abc uid 42 role "admin"
EXPIRE sess:abc 1800 -- 30 min TTL
HGETALL sess:abc