SoFunction
Updated on 2025-04-13

Detailed explanation of the five commonly used data types in Redis

Five common data types for Redis

1. String

Introduction

Strings are the most basic data type in Redis, and can store any type of data (such as text, numbers, binary data, etc.). The maximum length of each string can reach 512 MB.

Commonly used commands

SET key value

  • use: Set keykeyThe value ofvalue。
  • grammar：SET key value
  • Example：
SET username "john_doe"

GET key

  • use: Get keykeyvalue.
  • grammar：GET key
  • Example：
GET username

DEL key

  • use: Delete the specified keykey。
  • grammar：DEL key
  • Example：
DEL username

EXISTS key

  • use: Check keykeyWhether it exists.
  • grammar：EXISTS key
  • Example：
EXISTS username

INCR key

  • use: Turn keykeyThe value of 1 is added. If the key does not exist, it is initialized to 0.
  • grammar：INCR key
  • Example：
INCR page_views

DECR key

  • use: Turn keykeyThe value of 1 is reduced. If the key does not exist, it is initialized to 0.
  • grammar：DECR key
  • Example：
DECR user_count

APPEND key value

  • use: Change the string valuevalueAppend to keykeyafter the existing value.
  • grammar：APPEND key value
  • Example：
APPEND username "_2023"

MSET key1 value1 key2 value2 …

  • use: Set multiple key-value pairs at the same time.
  • grammar：MSET key1 value1 key2 value2 ...

Example：

MSET key1 "value1" key2 "value2"

MGET key1 key2 …

  • use: Get the values ​​of multiple keys.
  • grammar：MGET key1 key2 ...
  • Example：
MGET key1 key2

SETEX key seconds value

  • use: Set keykeyThe value ofvalue, and insecondsExpired in seconds.
  • grammar：SETEX key seconds value
  • Example：
SETEX session:123 3600 "abc123"  # set up1Expired after hours

Application scenarios

  • Cache system: Used to store user session information, web page content, etc. to improve data access speed.
  • counter: Implement simple counter functions, such as counting website visits, likes, etc.
  • Token storage: Store user's identity token in the authentication system.

2. Hash

Introduction

Hash is a mapping that stores key-value pairs, suitable for storing objects. Each hash supports up to 2^32-1 fields, which are usually used to represent a complex object.

Commonly used commands

HSET key field value

  • use: is a hash tablekeyFields infieldSet valuevalue。
  • grammar：HSET key field value
  • Example：
HSET user:1000 name "John Doe"

HGET key field

  • use: Get the hash tablekeyMedium fieldsfieldvalue.
  • grammar：HGET key field

Example：

HGET user:1000 name

HGETALL key

  • use: Get the hash tablekeyAll fields in and their corresponding values.
  • grammar：HGETALL key
  • Example：
HGETALL user:1000

HDEL key field

  • use: Delete the hash tablekeyFields infield。
  • grammar：HDEL key field
  • Example：
HDEL user:1000 age

HINCRBY key field increment

  • use: Convert hash tablekeyMedium fieldsfieldAdd the value ofincrement。
  • grammar：HINCRBY key field increment
  • Example：
HINCRBY user:1000 age 1

HKEYS key

  • use: Get the hash tablekeyall field names in
  • grammar：HKEYS key
  • Example：
HKEYS user:1000

HVALS key

  • use: Get the hash tablekeyAll field values ​​in
  • grammar：HVALS key
  • Example：
HVALS user:1000

HEXISTS key field

  • use: Check the hash tablekeyIs there a field in itfield。
  • grammar：HEXISTS key field
  • Example：
HEXISTS user:1000 name

HMSET key field1 value1 field2 value2 …

  • use: Set the values ​​of multiple fields at the same time.
  • grammar：HMSET key field1 value1 field2 value2 ...
  • Example：
HMSET user:1000 name "John Doe" age 30

HMGET key field1 field2 …

  • use: Get the values ​​of multiple fields in the hash table.
  • grammar：HMGET key field1 field2 ...
  • Example：
HMGET user:1000 name age

Application scenarios

  • User information storage: Use hash to store multiple attributes of users (such as username, age, address, etc.) to facilitate quick query and update.
  • Product Information Management: In the e-commerce system, the detailed information of the product (such as price, inventory, sales, etc.) is stored using hash.

3. List

Introduction

Lists are ordered collections of strings that support duplicate elements. The length of the list can reach 2^32-1 elements, which is suitable for implementing data structures such as queues and stacks.

Commonly used commands

LPUSH key value

  • use: Insert one or more values ​​into the listkeythe head.
  • grammar：LPUSH key value [value ...]
  • Example：
LPUSH tasks "Task 1"

RPUSH key value

  • use: Insert one or more values ​​into the listkeythe tail of the
  • grammar：RPUSH key value [value ...]
  • Example：
RPUSH tasks "Task 2"

LPOP key

  • use: Remove and return to the listkeyThe first element.
  • grammar：LPOP key
  • Example：
LPOP tasks

RPOP key

  • use: Remove and return to the listkeyThe last element of .
  • grammar：RPOP key
  • Example：
RPOP tasks

LRANGE key start stop

  • use: Get the listkeySpecify the elements within the range,startandstopis the index, and a negative number means the count starts from the end.
  • grammar：LRANGE key start stop
  • Example：
LRANGE tasks 0 -1  # Get the entire task list

LTRIM key start stop

  • use: Trim the listkey,reservestartarrivestopElements within range.
  • grammar：LTRIM key start stop
  • Example：
LTRIM tasks 0 4  # Only before5Elements

LINDEX key index

  • use: Get the listkeySpecify the index inindexelements.
  • grammar：LINDEX key index
  • Example：
LINDEX tasks 1  # Get the second task

LLEN key

  • use: Get the listkeylength.
  • grammar：LLEN key
  • Example：
LLEN tasks

RPOPLPUSH source destination

  • use: Remove the listsourceThe last element of the listdestinationthe head.
  • grammar：RPOPLPUSH source destination
  • Example：
RPOPLPUSH tasks completed_tasks

BRPOP key [key …] timeout

  • use: Block pop-up listkeyThe last element is until timeout or a new element is available.
  • grammar：BRPOP key [key ...] timeout
  • Example：
BRPOP tasks 5  # wait5Return in seconds

Application scenarios

  • Message Queue: Use lists to implement task queues and support FIFO (first-in, first-out) logic.
  • Time series data: Store user operation records or log information for chronological access.

4. Set

Introduction

Collections are unordered string collections that support adding, deleting and finding operations. Elements in the collection are unique, and repeated elements will be automatically ignored.

Commonly used commands

SADD key member [member …]

  • use: to the setkeyAdd one or more members.
  • grammar：SADD key member [member ...]
  • Example：
SADD myset "apple"

SREM key member [member …]

  • use: From the collectionkeyRemoves one or more members.
  • grammar：SREM key member [member ...]
  • Example：
SREM myset "banana"

SMEMBERS key

  • use: Get the collectionkeyAll members in
  • grammar：SMEMBERS key
  • Example：
SMEMBERS myset

SISMEMBER key member

  • use:Judge membersmemberIs it in the collectionkeymiddle.
  • grammar：SISMEMBER key member
  • Example：
SISMEMBER myset "apple"

SINTER key1 key2 [key3 …]

  • use: Returns the intersection of all sets given.
  • grammar：SINTER key1 key2 [key3 ...]
  • Example：
SINTER set1 set2

SUNION key1 key2 [key3 …]

  • use: Returns the union of all collections given.
  • grammar：SUNION key1 key2 [key3 ...]
  • Example：
SUNION set1 set2

SDIFF key1 key2 [key3 …]

  • use: Return to the collectionkey1The difference between other sets.
  • grammar：SDIFF key1 key2 [key3 ...]
  • Example：
SDIFF set1 set2

SPOP key [count]

  • use: Remove and return the collectionkeyOne or more random members in.
  • grammar：SPOP key [count]
  • Example：
SPOP myset 2  # Randomly remove and return2Members

SCARD key

  • use: Get the collectionkeynumber of members.
  • grammar：SCARD key
  • Example：
SCARD myset

SMOVE source destination member

  • use: to add membersmemberFrom the collectionsourceMove to collectiondestination。
  • grammar：SMOVE source destination member

Example：

SMOVE myset other_set "apple"

Application scenarios

  • Tag system: Use collections to store users’ interest tags to facilitate interest recommendations.
  • Statistics of independent users: Statistics the number of independent visitors or active users of the website, and uses the deduplication feature of the collection.

5. Ordered Set

Introduction

An ordered set is a string collection where each element is associated with a score, and the elements in the set are ordered. Members are unique, but scores can be repeated.

Commonly used commands

ZADD key score member [score member …]

  • use: To orderly setkeyAdd one or more members and their scores.
  • grammar：ZADD key score member [score member ...]

Example：

ZADD leaderboard 100 "player1"

ZRANGE key start stop [WITHSCORES]

  • use: Returns an ordered setkeyMembers within the specified interval.
  • grammar：ZRANGE key start stop [WITHSCORES]
  • Example：
ZRANGE leaderboard 0 -1 WITHSCORES  # Get all players and their scores

ZREM key member [member …]

  • use: Remove ordered collectionskeyOne or more members of the
  • grammar：ZREM key member [member ...]
  • Example：
ZREM leaderboard "player1"

ZRANK key member

  • use: Return to membermemberIn an ordered collectionkeyRanking in (start from 0).
  • grammar：ZRANK key member
  • Example：
ZRANK leaderboard "player2"

ZCARD key

  • use: Returns an ordered setkeynumber of members.
  • grammar：ZCARD key
  • Example：
ZCARD leaderboard

ZSCORE key member

  • use: Get an ordered collectionkeyMembersmemberscore.
  • grammar：ZSCORE key member

Example：

ZSCORE leaderboard "player2"

ZREVRANGE key start stop [WITHSCORES]

  • use: Returns an ordered set in order from high to lowkeyMembers within the specified interval.
  • grammar：ZREVRANGE key start stop [WITHSCORES]
  • Example：
ZREVRANGE leaderboard 0 -1 WITHSCORES  # Get all players and their scores，From high to low by score

ZINCRBY key increment member

  • use: Ordered collectionkeyMembersmemberAdd the score ofincrement。
  • grammar：ZINCRBY key increment member
  • Example：
ZINCRBY leaderboard 10 "player1"  # player1Increased scores10

ZPOPMIN key [count]

  • use: Remove and return an ordered collectionkeyOne or more members with the lowest score.
  • grammar：ZPOPMIN key [count]
  • Example：
ZPOPMIN leaderboard 1  # Remove and return the lowest score1Members

ZPOPMAX key [count]

  • use: Remove and return an ordered collectionkeyOne or more members with the highest score.
  • grammar：ZPOPMAX key [count]
  • Example：
ZPOPMAX leaderboard 1  # Remove and return the highest score1Members

Application scenarios

  • Ranking list: Score rankings used for games, popularity rankings on social media, etc.
  • Time-sensitive data: For example, the real-time recommendation system dynamically updates the recommended content based on the user's behavior score.

Summarize

By learning more about Redis’s various data types and their commonly used commands, developers can more effectively take advantage of the power of Redis. In high concurrency and high performance application scenarios, correctly selecting and using Redis's data structures and commands will significantly improve the performance and scalability of your application. Hope this article helps you with Redis!

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