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Redis data type

Redis supports five data types: string (string), hash (hash), list (list), set (collection) and zset (sorted set: ordered collection).

String (string)

String is the most basic type of redis, which you can understand as exactly the same type as Memcached, with a key corresponding to a value.

The string type is binary safe. It means that the string of redis can contain any data. Such as jpg images or serialized objects.

String type is the most basic data type of Redis, and a key can store 512MB as much as possible.

Example:

127.0.1 6379 > set name "runoob"

OK

127.0.0.1 purl 6379 > get name

"runoob"

In the above example, we used Redis's SET and GET commands. The key is name and the corresponding value is runoob.

Note: a key can store 512MB at most.

Hash (hash)

Redis hash is a collection of key-name pairs.

Redis hash is a mapping table for field and value of type string, and hash is particularly suitable for storing objects.

127.0.0.1 hmset user:1 username runoob password runoob points 6379 >

OK

127.0.0.1 purl 6379 > hgetall user:1

1) "username"

2) "runoob"

3) "password"

4) "runoob"

5) "points"

6) "200"

In the above example, the hash data type stores the user object that contains the user script information. In the example, we use the Redis hmset, hgetall commands, with user:1 as the key value.

Each hash can store 232-1 key-value pairs (over 4 billion).

List (list)

The Redis list is a simple list of strings sorted in the order in which they are inserted. You can add an element to the head (left) or tail (right) of the list.

Example:

127.0.0.1 purl 6379 > lpush runoob redis

(integer) 1

127.0.0.1 purl 6379 > lpush runoob mongodb

(integer) 2

127.0.0.1 purl 6379 > lpush runoob rabitmq

(integer) 3

127.0.0.1 lrange runoob 6379 > 010

1) "rabitmq"

2) "mongodb"

3) "redis"

Set (collection)

The Set of Redis is an unordered collection of type string.

The collection is implemented through a hash table, so the complexity of adding, deleting, and finding is all O (1).

Sadd command

Add a string element to the set collection corresponding to key, and successfully return 1. There is no return error if the element has already returned the set corresponding to 0MagneKey in the collection.

Example:

127.0.0.1 purl 6379 > sadd runoob2 redis

(integer) 1

127.0.0.1 purl 6379 > sadd runoob2 mongodb

(integer) 1

127.0.0.1 purl 6379 > sadd runoob2 rabitmq

(integer) 1

127.0.0.1 purl 6379 > sadd runoob2 rabitmq

(integer) 0

127.0.0.1 purl 6379 > smembers runoob2

1) "rabitmq"

2) "mongodb"

3) "redis"

Note: rabitmq has been added twice in the above example, but depending on the uniqueness of the elements in the collection, the second inserted element will be ignored.

The maximum number of members in the collection is 4294967295 (each collection can store more than 4 billion members).

Zset (sorted set: ordered set)

Redis zset, like set, is a collection of elements of type string, and duplicate members are not allowed.

The difference is that each element is associated with a score of type double. Redis sorts the members of the collection from small to large by scores.

The members of the zset are unique, but the score can be repeated.

Zadd command

Add an element to the collection, and update the corresponding score if the element exists in the collection

Zadd key score member

Example:

127.0.0.1 6379 > zadd runoob3 0 redis

(integer) 1

127.0.0.1 6379 > zadd runoob3 0 mongodb

(integer) 1

127.0.0.1 6379 > zadd runoob3 0 rabitmq

(integer) 1

127.0.0.1 6379 > zadd runoob3 0 rabitmq

(integer) 0

127.0.0.1 6379 > zrangebyscore runoob3 0 1000

1) "mongodb"

2) "rabitmq"

3) "redis"

Reference link:

Https://redis.io/topics/data-types-intro

Https://redis.io/topics/data-types

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