Redis overview installation

1、 Redis  It's an open source  key-value  The storage system . 
2、 and  Memcached  similar , It supports storage  value  There are more types , Include 
 string( character string )、 list( Linked list )、set( aggregate )、zset(sorted set 
 -- Ordered set ) and  hash（ Hash type ）.
 3、 These data types support  push/pop、add/remove  And intersection Union 
  Sum and difference sets and richer operations ,  And these operations are atomic .
 4、 On this basis ,Redis  Support various sorts of sorting .
 5、 And  memcached  equally , To ensure efficiency , The data is cached in memory .
 6、 The difference is  Redis  It will periodically write the updated data to disk or modify 
  Write the additional record file .
 7、 And on this basis to achieve  master-slave( Master-slave ) Sync .

1、 Application scenarios

1. Cache with relational database

      High frequency , Hot access data , Lower the database  IO 
      Distributed architecture , do  session  share 
   

2. A variety of data structures store persistent data
   

Redis Installation

Redis Official website
Redis Official website in Chinese
1、 Installed version

 6.2.1 for Linux（redis-6.2.1.tar.gz） 
  Don't think about it  windows  Environment  Redis  Support for 

2. Installation steps
   2.2.2.1. preparation ： Download and install the latest version of gcc compiler

     install  C  The compiling environment of language  
    yum install centos-release-scl scl-utils-build 
    yum install -y devtoolset-8-toolchain 
    scl enable devtoolset-8 bash 
     test  gcc  edition  
    gcc --version
   

2.2.2.2. download redis-6.2.1.tar.gz discharge /opt Catalog
2.2.2.3. Unpack the command ：tar -zxvf redis-6.2.1.tar.gz
2.2.2.4. After decompression, enter the directory ：cd redis-6.2.1
2.2.2.5. stay redis-6.2.1 Execute... Again in the directory make command （ only Is compiled ）
2.2.2.6. If not ready C Language compiling environment ,make Will be submitted to the wrong —Jemalloc/jemalloc.h： There is no such document
2.2.2.7. Solution ： function make distclean
2.2.2.8. stay redis-6.2.1 Execute... Again in the directory make command （ only Is compiled ）
2.2.2.9. skip make test Carry on : make install

2.2.3. The installation directory ：/usr/local/bin View the default installation directory ：
redis-benchmark: Performance testing tools , You can run it in your own book , Look at the performance of your book
redis-check-aof： Fix the problem AOF file ,rdb and aof Later on
redis-check-dump： Fix the problem dump.rdb file
redis-sentinel：Redis Cluster use
redis-server：Redis Server start command redis-cli： client , Operation entrance
2.2.4. The front desk starts （ Not recommended ）
The front desk starts , The command line window cannot be closed , Otherwise, the server stops .

2.2.5. Background start （ recommend ）
2.2.5.1. Backup redis.conf Copy a redis.conf Go to other directories cp /opt/redis-3.2.5/redis.conf /myredis
2.2.5.2. Background startup settings daemonize no Change to yes modify redis.conf(128 That's ok ) The document will contain daemonize no Change to yes, Let the service start in the background
2.2.5.3.Redis start-up redis-server/myredis/redis.conf
2.2.5.4. Use the client to access ：redis-cli
2.2.5.5. Multiple ports can ：redis-cli -p6379
2.2.5.6. Test verification ： ping
2.2.5.7.Redis close

 Single instance close ：redis-cli shutdown
 Multi instance shutdown , The specified port is closed ：redis-cli -p 6379 shutdown

2.2.6. Redis Introduce relevant knowledge

Redis A single thread + multiple IO Multiplexing technology
Multiplexing is the use of a single thread to examine multiple file descriptors （Socket） The ready state of , For example, call select and poll function , Pass in multiple file descriptors , If there is a file descriptor ready , Then return to , otherwise Block until timeout . After getting the ready state, the real operation can be executed in the same thread , You can also start Dynamic thread execution （ Like using thread pools ）

Serial vs Multithreading + lock （memcached） vs Single thread + multiple IO Reuse (Redis)
（ And Memcache Three different things : Supports multiple data types , Support persistence , Single thread + multiple IO Reuse ）