What does the time complexity column mean?

It is the Big-O cost of a single call, where N is the number of elements involved. Redis is single-threaded, so an O(N) command on a huge key blocks every other client until it finishes.

Why should I avoid KEYS in production?

KEYS scans the entire keyspace in one blocking O(N) operation, freezing the server on large databases. Use SCAN, which returns a cursor and iterates incrementally without blocking, instead.

What is the difference between SET with EX and EXPIRE?

SET key value EX 60 sets the value and a 60-second TTL atomically in one command. EXPIRE sets a TTL on a key that already exists. Using SET ... EX avoids a race where the key exists briefly without an expiry.

How are sorted sets ordered?

A sorted set (zset) keeps members ordered by an associated floating-point score. ZRANGE returns members by index from lowest to highest score, and ZRANGEBYSCORE returns members within a score window.

Are these the only Redis commands?

No. Redis has hundreds of commands including streams, pub/sub, transactions, scripting and server administration. This reference focuses on the core data-structure commands developers use most.

Redis Commands Reference

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A grouped, offline Redis command lookup

Redis commands map onto its data structures — strings, hashes, lists, sets and sorted sets — plus a set of generic key commands. This reference lets you search commands by name or description and filter by data structure, showing the syntax, the time complexity and the version each command appeared in. It runs entirely in your browser.

How it works

Each entry lists the command, the data structure it operates on, the syntax with placeholders, the Big-O time complexity and the Redis version it was introduced in. Because Redis executes commands one at a time on a single thread, the time complexity tells you whether a command is safe to run on a large key. A few common patterns:

SET session:42 "{...}" EX 3600      # value + 1-hour TTL atomically
INCR page:views                     # atomic counter
ZADD leaderboard 99 "alice"         # add scored member
ZRANGE leaderboard 0 9 WITHSCORES   # top 10 by score
SCAN 0 MATCH user:* COUNT 100       # iterate keys without blocking

Tips and examples

Prefer SCAN over KEYS and HSCAN/SSCAN/ZSCAN over their bulk equivalents on large keys to avoid blocking the server.
Always set an expiry on cache keys with EXPIRE or SET ... EX so memory does not grow unbounded.
Use BLPOP/BRPOP to build a simple blocking work queue without polling.
Sorted sets make excellent leaderboards and rate-limiters because score-based range queries are O(log N + M).