In this article, you can find the most useful Redis data structures with brief details for each.

To see all data structures, including extension data types, visit the link below:
Redis Data Types Documentation

The link below provides the time complexity for all Redis commands, which is very helpful in selecting the right data structure for your use case:
Redis Command Time Complexity Cheat Sheet

Strings

Redis strings store sequences of bytes, including text, serialized objects, and binary arrays.

Example

> SET bike:1 Deimos
OK
> GET bike:1
"Deimos"

Usage

• Storing simple key-value pairs

• Caching responses

• Counting (using INCR, DECR)

Important Notes

• Most string operations are O(1)

• Be careful with the SUBSTR, GETRANGE, and SETRANGE commands, which can be O(n)

• Redis string can be a maximum of 512 MB (Danger)

Helpful Links

https://redis.io/docs/latest/develop/data-types/strings

https://redis.io/docs/latest/commands/?group=string

Lists

Redis lists are ordered collections of strings, implemented as linked lists.

Example

> RPUSH todo:123 "Buy milk"
> RPUSH todo:123 "Walk the dog"
> LPUSH todo:123 "Check emails"
> LRANGE todo:123 0 -1
1) "Check emails"
2) "Buy milk"
3) "Walk the dog"

Usage

• Implementing queues (FIFO, LIFO)

• Twitter social network takes the latest tweets posted by users into Redis lists - reference

Important Notes

• Operations that access its head or tail are O(1)

• Commands that manipulate elements within a list are usually O(n) (Danger)

  • Like LINDEX, LINSERT, and LSET

• Redis streams is an alternative to lists when you need to store and process an indeterminate series of events

Helpful Links

https://redis.io/docs/latest/develop/data-types/lists

https://redis.io/docs/latest/commands/?group=list

Sets

Redis Set is an unordered collection of unique strings.

Example

> SADD users:online Alice
> SADD users:online Bob
> SADD users:online Alice
> SMEMBERS users:online
1) "Alice"
2) "Bob"

Usage

• Track unique items (e.g., track all unique IP addresses accessing a given blog post).

• Represent relations (e.g., the set of all users with a given role).

• Perform common set operations such as intersection, unions, and differences.

Important Notes

• Most set operations, including adding, removing, and checking whether an item is a set member, are O(1)

• SMEMBERS command is O(n) and returns the entire set in a single response

Helpful Links

https://redis.io/docs/latest/develop/data-types/sets

https://redis.io/docs/latest/commands/?group=set

Hashes

Redis hashes are key-value maps, useful for storing objects.

Example

> HSET user:100 name "Alice" age "30"
> HGET user:100 name
"Alice"
> HGETALL user:100
1) "name"
2) "Alice"
3) "age"
4) "30"

Usage

• Caching database rows and …

Important Notes

• New in Redis Community Edition 7.4 is the ability to specify an expiration time or a time-to-live (TTL) value for individual hash fields.

• Most Redis hash commands are O(1).

• A few commands and most of the expiration-related commands are O(n) (Danger)

  • Like HKEYS, HVALS, HGETALL

• The number of fields in a hash is limited only by the total memory available on the Redis server.

Helpful Links

https://redis.io/docs/latest/develop/data-types/hashes

https://redis.io/docs/latest/commands/?group=hash

Sorted Sets (Zsets)

Zsets store unique strings with an associated score for ordering.

Example

> ZADD leaderboard 100 "Alice"
> ZADD leaderboard 200 "Bob"
> ZADD leaderboard 150 "Charlie"
> ZRANGE leaderboard 0 -1 WITHSCORES
1) "Alice"
2) "100"
3) "Charlie"
4) "150"
5) "Bob"
6) "200"

Usage

• Leaderboards

• Rate limiters

Important Notes

• Most sorted set operations are O(log(n))

• ZRANGE command's time complexity is O(log(n) + m), where m is the number of results returned.

• You can think of sorted sets as a mix between a Set and a Hash. Like sets, sorted sets are composed of unique, non-repeating string elements, so in some sense a sorted set is a set as well.

Helpful Links

https://redis.io/docs/latest/develop/data-types/sorted-sets

https://redis.io/docs/latest/commands/?group=sorted-set

Streams

Streams are an append-only log-like data structure.

Example

> XADD mystream * sensor-id 1 temperature 22.5
> XREAD COUNT 1 STREAMS mystream 0
1) "mystream"
2) 1) 1) "timestamp"
      2) "sensor-id"
      3) "1"
      4) "temperature"
      5) "22.5"

Usage

• Event sourcing (e.g., tracking user actions, clicks, etc.)

• Sensor monitoring (e.g., readings from devices in the field)

• Notifications (e.g., storing a record of each user's notifications in a separate stream)

Important Notes

• Adding an entry to a stream is O(1)

• Accessing any single entry is O(n), where n is the length of the ID.

• Consumer groups allow fan-out processing and acknowledgments

• Fan-out with Consumer Groups: Multiple consumers in a group distribute messages (load balancing), while independent consumers (outside a group) receive all messages.

Helpful Links

https://redis.io/docs/latest/develop/data-types/streams

https://redis.io/docs/latest/commands/?group=stream

Geospatial indexes

Store and query geographic locations.

Example

> GEOADD locations 2.3522 48.8566 "Paris"
> GEOADD locations -74.0060 40.7128 "New York"
> GEODIST locations Paris "New York" km
"5837.2690"

Usage

• Location-based services

• Nearby search

Important Notes

• O(log n) complexity for GEOADD, GEODIST, GEORADIUS

Helpful Links

https://redis.io/docs/latest/develop/data-types/geospatial

https://redis.io/docs/latest/commands/?group=geo

Bitmaps

Bit-level operations for efficient storage and tracking.

Example

> SETBIT visits:20240403 0 1
> SETBIT visits:20240403 1 1
> GETBIT visits:20240403 0
1

Usage

• Efficient set representations for cases where the members of a set correspond to the integers 0-N.

• Object permissions, where each bit represents a particular permission, similar to the way that file systems store permissions.

Important Notes

• SETBIT and GETBIT are O(1)

• BITOP is O(n)

Helpful Links

https://redis.io/docs/latest/develop/data-types/bitmaps

https://redis.io/docs/latest/commands/?group=bitmap

JSON

Redis JSON provides structured, hierarchical arrays and key-value objects that match the popular JSON text file format.

Example

> JSON.SET bike:1 $ '{"brand":"Deimos","model":"X1","colors":["red","black"]}'
OK
> JSON.GET bike:1
"{\"brand\":\"Deimos\",\"model\":\"X1\",\"colors\":[\"red\",\"black\"]}"
> JSON.GET bike:1 $.brand
"[\"Deimos\"]"

Usage

• Storing complex structured data (objects, arrays)

• Querying specific fields or nested values with JSONPath ($.field)

• Caching structured API responses

• Managing hierarchical data like configurations, product catalogs, or user profiles

Important Notes

• JSON operations are generally efficient, but performance depends on document size and depth

• JSON supports numbers, strings, booleans, nulls, arrays, and objects (full JSON spec)

• Memory usage can grow quickly if storing large documents (Danger)

Helpful Links

https://redis.io/docs/latest/develop/data-types/json