Redis learning (I)

Redis Study ( One )

1. What is? Redis

1. Basic concepts

   Redis It's based on key value pairs NoSql database .

   Unlike many key value pair databases ,Redis The value in is yes string、hash、list、set、zset、Bitmaps、HyperLogLog、GEO And other data structures and algorithms , therefore redis It can satisfy many application scenarios , And because redis Will put all data in memory , So its read-write performance is amazing . More Than This ,redis The data in memory can also be saved to the hard disk in the form of snapshot and log , In case of power failure or failure , Data in memory will not be lost .
   Besides ,redis Key expiration is also provided 、 Publish subscribe 、 Business 、 Assembly line 、Lua Additional functions such as scripts .

2. redis The advantages of

1. Fast , Because the data is in memory , Be similar to HashMap,HashMap The advantage is the time complexity of both the lookup and the operation O(1)
2. Support for rich data types , Support string,list,set,sorted set,hash
3. Support transactions , The operations are all atomic , Atomicity means that changes to the data are either performed in full , Or none at all
4. Rich features ： Available for caching , news , Press key Set expiration time , It will be deleted automatically after expiration

2. redis Application scenarios of

1. cache
   • For some caches to be returned to the front-end data , When there are a lot of databases sql In operation , In order to avoid every interface request to query the database , You can cache some data to redis in , This is to get data directly from memory , The speed has increased a lot .
   • web End user , For login caching session data , Some of the login information is stored in session in , The cache to redis in .
2. queue
   • redis Provided in list Interface , This list Provides lpush and rpop, These two methods are atomic , You can insert queue elements and pop-up queue elements .
3. data storage
   • redis It's a non relational database , You can put redis Directly for data storage , It provides operations such as adding, deleting, modifying and checking , because redis There is a good hard disk persistence mechanism ,redis Data can be persisted to the hard disk on a regular basis , To ensure the redis Data integrity and security .
4. redis Lock realizes anti brush mechanism
   • redis Locks can handle concurrency issues ,redis One of the data types set type ,set Types are unordered when storing data , And each value is different , Can't repeat , In this way, you can quickly find out whether a value in an element exists , Add and delete exactly .

explain :redis The basic operation of the usage scenario will be in redis Study (3)- In the actual combat chapter .

3. redis Installation and startup

1. redis Installation

   1. ** Download address ：**https://github.com/tporadowski/redis/releases

   
   2. double-click ：Redis-x64-5.0.14.msi

   3. choice “ Agree to the agreement ”, Click next to continue .

   4. choice “ add to Redis Directory to environment variable PATH in ”, It is convenient for the system to identify automatically Redis Where is the execution file .

   5. The port number can remain the default 6379, And choose the firewall exception , So as to ensure that the external can be accessed normally Redis service .

   6. Set the maximum value to 100M. As an experiment and learning ,100M enough .

   7. After installed ：

      

      redis-server.exe： Server program , Provide redis service

      redis-cli.exe: Client program , Connect through it redis Service and operate

   8. Right click “ Computer ”> choice “ management ”. Find and click in the left column “ Computer management （ Local ）”> Services and Applications > service . And find it on the right Redis Service by name , Check the startup . If not started , Start it manually . Under normal circumstances , The service should be up and running properly .

   9. Set the password ( choose )：

      open redis-cli.exe

      CONFIG SET requirepass "yourpassword"
      

      or

      open redis.windows.conf The configuration file // window System is with windows Of ,linux System is redis.conf
      find requirepass foobared, Ahead of # Remove the number , hold foobared Change to password
      for example requirepass 123456

   10. test ：

       open redis-cli.exe

       Normal prompt entry , And display the correct port number , Indicates that the service has been started .

       

       Password verification is required before using the service . Input “auth 020826” And return （020826 It's the password set before ）.

       Return to the prompt OK Indicates that the verification passed .

4. redis Basic command

1. start-up redis command ：

   ./redis-server 
   #  Direct start redis, Sometimes you need to start the fixed configuration file （ Reset password ） Of redis,
   #  for example ：
   redis-server redis/redis.windows.conf
   #  perhaps 
   ./redis-server …/redis.conf
   

2. redis Service related commands

   #  Uninstall service ：
   redis-server --service-uninstall
   #  Start the service ：
   redis-server --service-start
   #  Out of Service ：
   redis-server --service-stop