Common redis data types and application scenarios

• Redis Command Reference
• Redis Official website Command Reference

Five common data types ： character string string, list list, hash hash, aggregate set, Ordered set sorted set

1. character string string：

The string type is Redis The most basic data storage type in , It's a sequence of bytes , He was in Redis Is binary safe , This means that the type can accept data in any format , It's standard key-value, It's usually used to store strings , Integers and floating point numbers .Value The maximum data length that can be accommodated is 512MB

Application scenarios ： A very common scenario is used to count the number of website visits , Number of people currently online, etc .incr command (++ operation )

2. list list：

Redis The list allows users to push or pop elements from both ends of the sequence , A list is an ordered, repeatable sequence of multiple string values , It's a list structure , So the time complexity of adding elements to both ends of the list is 0(1), The closer you get to both ends, the faster . This means even a list of tens of millions of elements , To obtain the head or tail of 10 Records are also very fast .List The maximum number of elements that can be contained in is 4294967295.
Application scenarios ：1. The latest news leaderboard .2. Message queue , To complete the message exchange between multiple programs . It can be used push The operation will cause the task to exist list in （ producer ）, Then the thread is in use pop The operation takes the task out for execution

3. hash hash：

Redis Hash in can be regarded as having String key and String value Of map Containers , Multiple key-value Store in a key in . every last Hash Can be stored 4294967295 Key value pairs .
Application scenarios ： Such as storage 、 Read 、 Modify user properties （name,age,pwd etc. ）

4. aggregate set：

Redis The set of is unordered and unrepeatable , Just like the list , When performing insert and delete and determining whether an element exists , Efficiency is very high . The biggest advantage of a set is that it can perform intersection, union and subtraction operations .Set The maximum number of elements that can be included is 4294967295.
Application scenarios ：1. Use intersection to find common friends .2. Using uniqueness , You can count all the independent websites you visit IP.3. Friends recommend according to tag Find the intersection , Greater than one threshold（ Of the critical value ） You can recommend .

5. Ordered set sorted set：

and set It's like , It's a collection of strings , Do not allow duplicate members to appear in a set in . The difference between them is that each member of the ordered set will have a score (score) Associated with it ,Redis It's the scores that sort the members of a collection from small to large . Although the members in the ordered set must be guards , But the score (score) But it can be repeated .
Application scenarios ： Can be used for a large online game ranking , Whenever a player's score changes , It can be executed zadd Update player scores (score), After that, we passed zrange Get some points top ten User information for .

Last , There's another one right key General operation of , All data types can be used

Reprinted from ：https://blog.csdn.net/m0_54425879/article/details/116783792