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Redis traditional 5. The application of big data type

Landing application of redis traditional 5 big data type

Redis introduction:

Redis is an open source (BSD licensed), in-memory data structure storage system that can be used as database, cache, and messaging middleware. It supports many types of data structures, such as string (strings), hash (hashes), list (lists), set (sets), ordered set (sorted sets)] and range query, bitmaps, hyperloglogs and geospatial (geospatial) index radius query. Redis has built-in replication (replication), LUA script (Lua scripting), LRU driven event (LRU eviction), transaction (transactions) and different levels of disk persistence (persistence), and provides high availability (high availability) through Redis Sentinel (Sentinel) and automatic partitioning (Cluster).

Note: the redis command is not case-sensitive, while 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,]

Numerical increase or decrease

Incremental digital incr key

Increase the specified integer incrby key increment

Decreasing value decr key

Reduce the specified integer decrby key decrement

Get character length

STRLEN key

Distributed lock

Setnx key value

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

EX: how many seconds before key expires

PX: how many milliseconds since key expires

NX: create a key. NX when key does not exist. The effect is equivalent to that of setnx

XX: overrides key when key exists

Application scene

Item number and order number are generated by INCR command

Do you like to like the article?

Readings: 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 a time

HMSET key field value [fild value...]

Get more than one field value at a 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 scenario

In the early days of shopping carts, small and medium-sized factories can now use them.

New products-- > hset shopcar:uid1024 334488 1

New products-- > hset shopcar:uid2014 334477 1

Increase the number of goods-- > hincrby shopcar:uid1024 334477 1

Total number of goods-- > hlen shopcar:uid1024

Select all-- > hgetall shopcar:uid1024

List list type

Add an element to the left of the list

Lpush key value [value...]

Add an element to the right of the list

Rpush key value [value...]

View list

Lrange key start stop

Gets the number of elements in the list

Llen key

Command u

Application scenario

Wechat articles subscribe to official account

1. [xxbao] and [xxbao] published articles 11 and 22 respectively

2. The author follows both of them, and whenever they post a new article, they will push it to my list.

Lpush likearticle: uid1024 11 22

3. Check all the author's own Subscription account articles, which are similar to pagination. The following 0-10 shows 10 lrange likearticle:uid1024 0 10 at a time.

Set does not repeat list types

Add element

Sadd key member [member...]

Delete element

Srem key member [member...]

Get all the elements of the collection

Smembers key

Determine whether the element is in the collection

Sismember key member

Gets the number of elements in the collection

Scard key

An element pops up randomly from the collection and is not deleted

Srandmember key [digital]

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

Spop key [digital]

Set operation

Subtraction operation A-B of a set

A collection of elements that belong to A but not to B.

Sdiff key [key...]

The intersection element of a set is A ^ B

It belongs to the elements jointly owned by An and B.

Simter key [key...]

Union operation A v B of a set

A merged collection of elements that belong to An or B

Sunion key [key...]

Application scene

Wechat lucky draw Mini Program

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

2. Show how many people have participated and currently 67231 people have participated, scard key

3. Draw lottery (randomly select N winners from set)

Srandmember key 2 draws 2 people randomly, the element will not be deleted.

Spop key 3 driver draw 3 people, the element will be deleted.

Like on Wechat moments.

1. Add likes; sadd pub:msgid likes users id1 likes users id2

2. Cancel likes; srem pub:msgid likes users id

3. Show smembers pub:msgid of all users who have been liked.

4. Statistics on the number of like users, which is the common red number scard pub:msgid to be liked.

5. Judge whether a friend likes the building master too much. Sismember pub:msgid user id

Weibo friends pay attention to social relationships.

People of common concern

Sadd s1 1 2 3 4

Sadd s2 2 3 6 8

Sinter s1 s2

Common concern: I go to someone's Weibo and immediately get someone who shares their attention.

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

I followed Huawei Yu Chengdong, and Yu Chengdong also followed Zhang Zhaozhi. Yu and I have common hobbies.

Sadd s1 1 2 3 4 5

Sadd s2 3 4 5 6 7

Sismember s1 3

Sismember s2 3

QQ tweets 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 command

1. Add an element and its score to the ordered collection

2. Add elements

ZADD key score member [score member...]

3. Return all elements indexed from strat to stop in the order in which the element scores arrive.

Zrange key start stop [WITHSORES]

4. Get the score of the element

Zscore key member [member...]

5. Delete elements

Zrem key member [member...]

6. Get the elements in 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 number of elements in the collection

Zcard key

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

Zcount key min max

10. Delete elements according to the ranking range

Zremrangebyrank key start stop

11. Get the ranking of elements

Zrank key member from small to big

From big to small zrevrank key member

Application scenario

1. More merchandise sales to sort the goods and display them.

Idea: define the ranking of commodity sales (sorted set collection). Key is goods:sellsort and the score is the number of goods sold.

The sales volume of item no. 1001 is 9, and that of item no. 1002 is 15 | zadd goods:sellsort 9 1001 15 1002

One customer bought two more items 1001. The item number is 1001 and increases by 2. | zincrby goods:sellsort 2 10001

Ask for the top 10 merchandise sales zrange goods:sellsort 0 10 withscores

2. Hot search on Douyin

1. Click on the video

ZINCRBY hotavi:20220203 1,800

ZINCRBY hotavi:20220203 15 eight hundred two Mulan

2. Top 10 items on the day of display

Zrevrange hotavi:20220203 0 9 withscores

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