Read write separation master-slave replication of MySQL

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The opening

Read and write all the pressure to amuse a database to bear , High pressure , If the database server disk is damaged, the data will be lost , A single point of failure , It can realize the read-write separation of multiple databases

One 、Mysql Master slave copy

（1） Introduce

Mysql The master-slave replication of is an asynchronous replication process , The bottom layer is based on Mysql Binary log function of database . It means that one machine will have more than one Mysql database （slave, From the library ） From the other Mysql database （maseter, The main library ）, Copy the log, then parse the log and apply it to itself , Finally, the data of the slave database is consistent with that of the master database .Mysql The master-slave copy of Mysql The functions of the database , No need to use third-party tools ;

Mysql The replication process is divided into three steps ：

• master Record changes to binary （binary log）
• slave take master Of binary log Copy to its trunk log （relay log）
• slave Redo events in relay log , Apply the changes to your own database
  

（2） To configure

（1）

（2）

The server is unique Id It's not fixed

（3）

（4）
Create a new user in the main library , To facilitate data access from the library ;

(5) see Master Log file path for the library , Note that the file path will change when you execute the following commands before executing other commands , So try not to perform other operations

（6） Configuration from library

（7）

（8） Configure according to the previously configured information
（9） Check whether the slave database has been configured

（10） To test , Perform an operation in the main library , You can also see the result of the operation from the library ;

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Two 、 Read write separation cases

（1） background

In the face of increasing system access , The throughput of the database is facing a huge bottleneck , For applications with a large number of concurrent operations and fewer write operations at this time , Split the database into master and slave , The main database is responsible for transactional addition, deletion, modification and query , The slave library is responsible for query operations , It can effectively avoid row lock caused by data update , The query performance of the whole system has been greatly improved ;

（2）Sharding-JDBC Introduce

（3）sharding-jdbc Use

1. Import maven coordinate
   

2. Configure the read-write separation rule in the configuration file

spring:
  shardingsphere:
    datasource:
      names:
        master,slave
      #  The main data source 
      master:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://192.168.138.100:3306/rw?characterEncoding=utf-8
        username: root
        password: root
        
      #  From a data source , Can be more 
      slave:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://192.168.138.101:3306/rw?characterEncoding=utf-8
        username: root
        password: root
    masterslave:
      #  Read write separation configuration , Load balancing 
      load-balance-algorithm-type: round_robin # polling 
      #  The final data source name 
      name: dataSource
      #  Main database data source name 
      master-data-source-name: master
      #  From the list of library data source names , Multiple commas separate 
      slave-data-source-names: slave
    props:
      sql:
        show: true # Turn on SQL Show , Default false

3. Allow... To be configured in the configuration file bean Define override configuration items
   Created after datasource It's going to cover the front datasource;
   

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