Summary of Redis's five data types

This article brings you relevant knowledge about Redis, which mainly introduces related issues about data types, including string types, hash types, list types, collection types and Orderly collection, let’s take a look at it, I hope it will be helpful to everyone.

Recommended learning: Redis video tutorial

1. The 5 data types of Redis

redis is a An advanced key-value storage system, in which value supports five data types:

Key values ​​supported by Redis Data type

stringString Type

hash table type

list list type

##set collection type

zset ordered set type

Regarding the definition of key, please note the following points:

It is not recommended that the key name is too long, usually no more than 1024, if it is too long it will Affects query speed.
1. It is not recommended to be too short, as it will reduce readability.
2. Generally in companies, there is a unified naming standard.

2. String type string

2.1 Overview

The string type is the most basic data storage type in Redis. It is stored in binary in Redis. There is no encoding and decoding process. Regardless of whether the type stored is a string, integer, or floating point type, it will be written as a string. In Redis, the maximum data length that the string type Value can hold is 512M. This is the most commonly used data type in the future.

2.2 Common commands

Add 1 to the redis database Key and value of string type, return OK to indicate successful addition. The one with the same name will replace from the database Take out the value of a specified key, if there is a return value, if not return nilDelete the specified key and value. If the deletion is successful, return the number deleted. Otherwise return 0 If the setting is successful, 1 will be returned. Setup fails and returns 0.

2.3 Command Demonstration

Requirements:

1. Add a key as company, the value is itcast
2. Then set a key as company, the value is heima
3. Get the company element
4. Delete the company element
5. Delete the company again to see if the return value is the same
6. Get the company and see what the return value is
7. Set the key to job and the value to programmer
8. Set the value of job to code-farmer again and query the value of job

2.4 Execution effect

3. Hash

3.1 Overview

# Redis can be regarded as the MAP container with the key and String of String, each hash can store 40 Billions of key-value pairs.

So this type is very suitable for storing object information. If a user has name, password, age and other information, it can have keys such as username, password and age. Its storage structure is as follows:

3.2 Common commands

##Command	Behavior
set key value
get key
del key
##setnx key value When the specified key does not exist, set the specified value for the key.

##mulitple , set multiple field names and values ​​to a key at one time hdel key##hgetall key

Order	Behavior
##hset key field value	Add a pair of hash type field names and values ​​to the specified key
hget key Field	Get the value of the specified field of the specified key
hmset key Field valueField value
##hmget ## Key Field fieldGet the values ​​of multiple fields from the specified key at one time
field field Delete one or more fields in a key
Get all field values ​​​​of a certain key	# 3.3 Command Demonstration Requirements: Create a hash type key as user, and add a field as username, with a value of newboy Add a field to user as password, the value is 12345 Add the field age to user, the value is 18 Get the field values ​​​​of username, password and age in user respectively Add multiple fields and values ​​to user at the same time, birthday 2018-01-01 sex male Get multiple fields at the same time: age and sex Get all the fields and values ​​​​in user Delete the birthday and password fields in user 4. List type list 4.1 Overview In Redis, the List type is a linked list of strings sorted in insertion order. Like an ordinary linked list in the data structure, we can add new elements to its left and right parts. During insertion, if the key does not exist, Redis will create a new linked list for the key. If the key already exists, it will add elements to the list. In contrast, if all elements in the linked list are removed, the key will also be deleted from the database. The maximum number of elements that can be contained in a List is 4 billion. 4.2 Common commands right push adds a list element to the specified key on the right side of the list#left pop pops an element from the left of the specified key, and the element in the list is deleted. right pop from the specified key When an element pops up on the right, the element in the list is deleted. ##llen ##Command Behavior lpush key element element left push to the left of the list Adds a list element to the specified key. If the key does not exist, Redis will create a new linked list for the key. If the key already exists, it will add elements to the list. ##rpush key element element lpop key rpop key ##lrange key Start end Retrieve a list of elements in the specified range from the list of the specified key, counting from the left starting from 0, and counting from the right starting from -1. If you want to take the entire list, the start is 0 and the end is -1 KeyGet the length of the specified list 4.3 Command demonstration Execution effect Requirements: To the list of mylist keys, add a b c from the left Element Add one two three three elements from the right Query all elements Add a repeated element three# from the right ##Delete the rightmost element three Delete the leftmost element c Get the elements in the list Number of 5. Set type set 5.1 Overview In Redis, we can regard the Set type as unsorted Character collection, like the List type, we can also perform operations such as adding, deleting, or determining whether an element exists on the data values ​​of this type. The maximum number of elements that a Set can contain is 4 billion. Unlike the List type, duplicate elements are not allowed in the Set collection. 5.2 Common commands ##smemberssismembersrems ##Command Behavior s##add key element element Add 1 or more elements to the set collection KeyQuery all elements in the specified collection Key ElementDetermine whether the specified element is in a certain collection. If it exists, return 1, otherwise return 0 Key Element Elementremove Delete the specified element or elements union key 1 key 2 Returns the union of the given sets. A set key that does not exist is considered an empty set. 5.3 Command Demonstration Requirements: Add six elements A B C 1 2 3 to the myset collection Add the B element to myset to see if it can be added Success Displays all members and finds that the order of the elements is different from that of the added elements. The elements are unordered Delete the C element and check the result again Determine whether A In the myset set Determine whether D is in the myset set Create a set with the key set1: the element is a b c Create a set with the key set2: the element is a b d Get the union of set1 and set2, and display 6. Ordered set zset 6.1 Overview Redis ordered collections, like sets, are unordered and cannot be repeated. The difference is that each element is associated with a score. Redis uses scores to sort the members of the collection from small to large. The members of an ordered set are unique, but the scores can be repeated, and each set can store more than 4 billion members. 6.2 Common commands Return the members in the specified range in the ordered set through the index range##zcard key##zscore keyAdd the key country, the score is 10, the value is JapanAdd the key country, the score is 5, the value is USA ##Command Behavior zadd key Score value Score value To an ordered set Add one or more members ##zrange key Start index End index ##zrem Key Value Remove one or more members from the ordered set zrank key value Returns the index of the specified member in the ordered set Get the number of members of the ordered set ValueGet the score of the specified member ## 6.3 Command Demonstration Add the key country, the score is 1, the value is China , the score is 120, and the value is Korea Query all elements in country Query the index number of Japan (starting from 0) Delete elements with value USA Query how many elements there are in country 6.4 Effect Recommended learning: Redis video tutorial

The above is the detailed content of Summary of Redis's five data types. For more information, please follow other related articles on the PHP Chinese website!