Redis Data Types Overview

5. Redis Data Types Overview

Redis is not just a simple key-value store. It supports multiple rich data structures, each designed for specific use cases.

Data Type	Best Used For	Real-World Example
String	Simple values, counters, cached HTML	Page view counter, session token
List	Ordered collections, queues, timelines	Task queue, activity feed
Set	Unique collections, memberships	Unique visitors, user tags
Sorted Set	Ranked collections with scores	Leaderboard, trending topics
Hash	Object-like storage with fields	User profile, product details
Bitmap	Bit-level operations	Daily active users tracking
HyperLogLog	Approximate unique count	Unique website visitors (approximate)
Stream	Append-only log, event sourcing	IoT sensor data, event logs

Data Type Hierarchy Diagram

flowchart TB
    Core[Core Data Types] --> String["🔤 String<br/>Counters, tokens<br/>SET / GET / INCR"]
    Core --> List["📋 List<br/>Queues, timelines<br/>LPUSH / RPOP / LRANGE"]
    Core --> Set["🔢 Set<br/>Unique members, tags<br/>SADD / SINTER / SUNION"]
    Core --> SortedSet["🏆 Sorted Set<br/>Leaderboards, rankings<br/>ZADD / ZRANGE / ZREVRANK"]
    Core --> Hash["🗂️ Hash<br/>Objects, profiles<br/>HSET / HGET / HGETALL"]

    Advanced[Advanced Data Types] --> Stream["📡 Stream<br/>Event logs, messaging<br/>XADD / XREAD / XREADGROUP"]
    Advanced --> Bitmap["🟩 Bitmap<br/>Flags, DAU tracking<br/>SETBIT / GETBIT / BITCOUNT"]
    Advanced --> HLL["📊 HyperLogLog<br/>Approx unique counts<br/>PFADD / PFCOUNT"]
    Advanced --> Geo["📍 Geospatial<br/>Nearby places<br/>GEOADD / GEOSEARCH"]

    style Core fill:#7c3aed,color:#fff
    style String fill:#3b82f6,color:#fff
    style List fill:#3b82f6,color:#fff
    style Set fill:#3b82f6,color:#fff
    style SortedSet fill:#3b82f6,color:#fff
    style Hash fill:#3b82f6,color:#fff
    style Advanced fill:#059669,color:#fff
    style Stream fill:#059669,color:#fff
    style Bitmap fill:#059669,color:#fff
    style HLL fill:#059669,color:#fff
    style Geo fill:#059669,color:#fff

Tip: Strings, Lists, Sets, Sorted Sets, and Hashes are the 5 core types you’ll use daily. Streams, Bitmaps, HyperLogLog, and Geospatial are advanced types for specific use cases.