Through commands and application scenarios, we will guide you to understand the five basic types in Redis.

This article will introduce you to the five basic types in Redis through commands and application scenarios. There are many commands and practices. I hope it will be helpful to everyone!

redis The application of traditional 5 big data types

redis The implementation of traditional 5 big data types

Redis introduction:

Redis is an open source (BSD licensed), in-memory data structure storage system that can be used as a database, cache, and messaging middleware. It supports many types of data structures such as strings, hashes, lists, sets, sorted sets] with range queries, bitmaps, hyperloglogs and geospatial (geospatial) Index radius query. Redis has built-in replication, LUA scripting, LRU eviction, transactions and different levels of disk persistence, and through Redis Sentinel and automatic partitioning (Cluster) ) provides high availability. [Related recommendations: Redis video tutorial]

redis command query: http://www.redis.cn/commands.html

Note: redis commands are not size sensitive Write, and key is case-sensitive

Query command help:

help @type noun

Example:

string String type

Most commonly used

## set key vuue

getkey

Set/get multiple key values ​​at the same time

MSET key value [key value .. .]

MGET key [key ,,,]

Increase and decrease the value

increment the number incr key

Increase the specified integer incrby key increment

Decrease the numerical decr key

Decrease the specified integer decrby key decrement

Get the character length

STRLEN key

Distributed lock

setnx key value

set key value [EX seconds] [PX milliseconds] [NX|XX]

EX: how many seconds does the key expire after?
• PX: key since Expiration after how many milliseconds
• NX: When the key does not exist, the key is created. The effect is equivalent to setnx
• XX: When the key exists, overwrite the key

Application scenarios

The product number and order number are generated using the INCR command
• Yes Like the article

Reading count: As long as you click on the rest address, directly use the incr key command to add a number 1 to complete the recording of the number.

Command practice

hash Hash type

and Java data structure mapping

Map>

##Set one field value at a time HSET key field value

Get one field value at a time

HGET key field

Set multiple field values ​​at one time

HMSET key field value [fild value ...]

Get multiple field values ​​at one time

HMGET key field [field ...]

Get all field values

hgetall key

Get all the quantities in a key

hlen

Delete a key

hdel

Command demonstration

Application scenariosIn the early days of the shopping cart, currently small and medium-sized factories can use

to add new products --> hset shopcar:uid1024 334488 1

Add new product--> hset shopcar:uid2014 334477 1

Add product quantity--> hincrby shopcar:uid1024 334477 1

product Total --> hlen shopcar:uid1024

Select all --> hgetall shopcar:uid1024

list List type

Add elements to the left of the list

lpush key value [value ...]

Add elements to the right of the list

rpush key value [value ...]

View the list

lrange key start stop

Get the elements in the list Number

llen key

Command usage

Application scenario

WeChat article subscription public account

1, [xx treasure] and [xx newspaper] published articles 11 and 22## respectively

#2. The author follows both of them. As long as they publish a new article, it will be pushed to my list

lpush likearticle: uid1024 11 22

3. View the author All articles of your own subscription account are similar to paging. The following 0-10 is to display 10 items at a time lrange likearticle:uid1024 0 10

set Non-duplicate list type

Add element

sadd key member [member ...]

Delete element

srem key member [member ...]

Get all elements of the collection

smembers key

Judge whether the element is in the collection

sismember key member

Get the number of elements in the collection

scard key

From the collection Randomly pop up an element from the collection, the element will not be deleted

srandmember key [number]

Randomly pop up an element from the collection, delete one element

spop key [Number]

Set operation

• Difference operation of sets A - B

A set constructed from elements that belong to A but not B

sdiff key [key ...]

• The intersection of the sets is calculated as A ^ B

Elements that belong to A and also belong to B.

simter key [key ...]

• Union of sets Operation A v B

The merged set of elements belonging to A or B

sunion key [key ...]

Application Scenario

WeChat Lottery Mini Program

1. User id, participate immediately, sadd key user id

2. Display how many people have participated. There are currently 67231 people participating. scard key

3. Lottery (arbitrarily select N winners from the set)

srandmember key 2 random If you draw 2 people, the elements will not be deleted

spop key 3 Drivers draw 3 people, the elements will be deleted

Likes in WeChat Moments

1. Add a like; sadd pub:msgid like user id1 like user id2

2. Cancel like; srem pub:msgid like user id

3. Show all points Users who have liked smembers pub:msgid

4. Statistics of the number of users who like it, which is the common red number waiting for likes. scard pub:msgid

5. Determine whether a friend is right The author liked it, sismember pub:msgid user id

Weibo friends follow social relationships

People who follow together

sadd s1 1 2 3 4

sadd s2 2 3 6 8

sinter s1 s2

Common attention: I go to someone’s Weibo and immediately get the information that is shared with someone People

The people I follow also follow him (we all have the same hobbies)

I follow Yu Chengdong of Huawei, Yu Chengdong also follows Zhang Zhaodong, Mr. Yu and I have the same hobbies

sadd s1 1 2 3 4 5

sadd s2 3 4 5 6 7

sismember s1 3

sismember s2 3

QQ Recommend people you may know

sadd s1 1 2 3 4 5

sadd s2 3 4 5 6 7

// Common friends

sinter s1 s2

// Difference set

sdiff s1 s2

sdiff s2 s1

zset ordered set

Common commands

1. Add an element and the score of the element to the ordered set

2. Add element

ZADD key score member [score member ...]

3. Return all elements with index from strat to stop in the order of arrival of element scores

zrange key start stop [WITHSORES]

4. Get the score of the element

zscore key member [member ...]

5. Delete Element

zrem key member [member ...]

6. Get the elements of the specified score range

zrangebyscore key min max [ WITHSCORES] [LIMIT offset count]

7. Increase the score of an element

zincrby key increment member

8. Get the set The number of elements in

zcard key

9. Obtain the number of elements within the specified score range

zcount key min max

10. Delete elements according to ranking range

• zremrangebyrank key start stop

11. Get the ranking of elements

• zrank key member

• Zrevrank key member from large to small

Application scenarios

1. More product sales Sorting and displaying products

Idea: Define the product sales ranking list (sorted set), the key is goods:sellsort, and the score is the product sales quantity.

The sales volume of product number 1001 is 9, and the sales volume of product number 1002 is 15 | zadd goods:sellsort 9 1001 15 1002
A customer bought 2 more items Product 1001, the product number is 1001 loudly increase 2 | zincrby goods:sellsort 2 10001
Find the top 10 products by sales zrange goods:sellsort 0 10 withscores

2. Douyin hot search

1. Click on the video

ZINCRBY hotavi:20220203 1 八百

ZINCRBY hotavi :20220203 15 Eight Hundred 2 Hua Mulan

2. Display the top 10 items on the day

zrevrange hotavi:20220203 0 9 withscores

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