Redis of NoSQL database (I): Installation & Introduction

Redis summary

Redis It's an open source key-value The storage system .
Redis It's open source （BSD The license ） Of , Data structure storage system in memory , It can be used as a database 、 Caching and message middleware . It supports multiple types of data structures , Such as character string （strings）, hash （hashes）, list （lists）, aggregate （sets）, Ordered set （sorted sets） And scope query , bitmaps, hyperloglogs and Geographical space （geospatial） Index radius query . Redis Built in Copy （replication）,LUA Script （Lua scripting）, LRU Driving events （LRU eviction）, Business （transactions） And different levels of Disk persistence （persistence）, And pass Redis sentry （Sentinel） And automatic Partition （Cluster） Provide high availability （high availability）.

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 ）.

These data types support push/pop、add/remove And take intersection, union and difference sets and more abundant operations , And these operations are atomic .

On this basis ,Redis Support various sorts of sorting .
And memcached equally , To ensure efficiency , The data is cached in memory .
The difference is Redis Periodically, updated data is written to disk or changes are written to an appended log file .
And on this basis to achieve master-slave( Master-slave ) Sync .

Redis Application scenarios

Cache with relational database

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

A variety of data structures store persistent data

Redis install

1、 install 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、 Download and install Redis

Redis Official website ：http://redis.io
Redis Official website in Chinese ：http://redis.cn/

1、 Download from the official website redis-6.2.1.tar.gz Rear release /opt Catalog

2、 Unpack the installation redis-6.2.1.tar.gz

#  Unpack the command ：
tar -zxvf redis-6.2.1.tar.gz
#  After decompression, enter the directory ：
cd redis-6.2.1

#  stay redis-6.2.1 Execute... Again in the directory make command （ Just compile ）
make install
	 If not ready C Language compiling environment ,make  Will report a mistake —Jemalloc/jemalloc.h： There is no such document 
	#  Solution ： Carry out orders make distclean after , stay redis-6.2.1 Execute... Again in the directory make install command （ Just compile ）

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 

4、 start-up / close redis server

• The front desk starts ：

    #  The front desk starts （ Not recommended ）, The command line window cannot be closed , Otherwise, the server stops 
    redis -server
  

• Background start ：

  1、 Backup redis.conf

    #  A copy of  redis.conf  Go to other directories 
    cp  /opt/redis-3.2.5/redis.conf  /myredis
  

  2、 modify redis.conf（128 That's ok ）： Background startup settings daemonize no Change to yes

  3、Redis start-up

    #  start-up  redis
    redis-server /myredis/redis.conf
  

  4、 Test verification

    #  visit  redis
    redis-cli
    #  Port access  redis
    redis-cli -p6379
  
    [[email protected] bin]# redis-cli
    127.0.0.1: 6379>
    127.0.0.1: 6379> ping
    PONG
  

  5、Redis close

    #  Single instance close ：
    redis-cli shutdown
    #  The specified port is closed ：
    redis-cli -p 6379 shutdown
  
    #  You can also enter the terminal and then close it 
    redis-server /myredis/redis.conf
    shutdown	
  

Redis A single thread + multiple IO Multiplexing technology

 port 6379 To come from ：
	 Default 16 A database , Similar array subscript from 0 Start , Initial default use 0 Signal library 
	 Use command  select  <dbid>  To switch databases . Such as : select 8 
	 Unified password management , All libraries have the same password .
	dbsize ： Check the... Of the current database key The number of 
	flushdb ： Empty the current library 
	flushall ： Kill all the warehouses 

Redis A single thread + multiple IO Multiplexing technology .

Multiplexing It refers to using one thread to check 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 it blocks until it times out . After getting the ready state, the real operation can be executed in the same thread , You can also start 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 ）