Lists & Sets

Redis · Reference cheat sheet

📋 Overview

Lists are ordered sequences (queues, timelines). Sets are unordered unique collections (tags, membership). Both are foundational for queues and relationships.

🔧 Core concepts

💡 Examples

Simple queue:

LPUSH jobs '{"id":1}'
BRPOP jobs 5

Tags set:

SADD post:9:tags redis cache
SISMEMBER post:9:tags redis
SINTER user:1:tags user:2:tags

Recent items (list trim):

LPUSH feed:42 itemA
LTRIM feed:42 0 99

⚠️ Pitfalls

• SMEMBERS / large LRANGE can block — use SSCAN / limit ranges.
• Lists allow duplicates; sets do not — pick the right structure.
• Blocking pops need careful timeouts in app servers to avoid stuck workers.

🔗 Related

• sorted_sets.md
• hashes.md
• pubsub.md
• strings.md