6 ShardingSphere 主從複製讀寫分離

1 讀寫分離原理

爲了確保數據庫產品的穩定性，很多數據庫擁有雙機熱備功能，也就是，第一臺數據庫服務器對外提供增刪改業務的生產服務器，第二臺數據庫服務器，主要進行讀的操作。

原理：讓主數據庫（master）處理事務性增刪改操作，而從數據庫（slave）處理select 查詢操作。

2 Mysql 配置主從複製

2.1 創建2個Mysql 數據庫服務，並啓動兩個Mysql服務

2.2 配置Master庫的/etc/my.cnf

[mysqld]
basedir=/usr/local/mysql
datadir=/usr/local/mysql/data
socket=/tmp/mysql.sock
user=mysql
port=3306

# Master
# 開啓日誌
log-bin = mysql-bin
# 日誌格式按行同步
binlog-format = ROW
# 設置服務id，主從不能一致
server-id = 1
# 設置需要同步的數據庫
binlog-do-db = user_db
# 設置忽略系統庫同步
binlog-ignore-db = mysql
binlog-ignore-db = information_schema
binlog-ignore-db = performance_schema
binlog-ignore-db = sys

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

# character config
character_set_server=utf8mb4

[mysqld_safe]
log-error=/usr/local/mysql/data/mysql.log
pid-file=/usr/local/mysql/data/mysql.pid

# include all files from the config directory

!includedir /etc/my.cnf.d

主要配置

# Master
# 開啓日誌
log-bin = mysql-bin
# 日誌格式按行同步
binlog-format = ROW
# 設置服務id，主從不能一致
server-id = 1
# 設置需要同步的數據庫
binlog-do-db = user_db
# 設置忽略系統庫同步
binlog-ignore-db = mysql
binlog-ignore-db = information_schema
binlog-ignore-db = performance_schema
binlog-ignore-db = sys

2.3 配置Slave庫的/etc/my.cnf

[mysqld]
basedir=/usr/local/mysql
datadir=/usr/local/mysql/data
socket=/tmp/mysql.sock
user=mysql
port=3306

# Slave
# 開啓日誌
log-bin = mysql-bin
# 日誌按照行進行數據同步
binlog-format = ROW
# 設置服務id，主從不能一致
server-id = 2
# 設置需要同步的數據庫
replicate-do-db=user_db
# 設置忽略系統庫
replicate-ignore-db = mysql 
replicate-ignore-db = information_schema 
replicate-ignore-db = performance_schema 
replicate-ignore-db = sys

#replicate-wild-ignore_table = mysql.%
#replicate-wild-ignore_table = information_schema.%
#replicate-wildignore_table = performance_schema.%
#replicate-wild-ignore_table = sys.%

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

#character config
character_set_server=utf8mb4

[mysqld_safe]
log-error=/usr/local/mysql/data/mysql.log
pid-file=/usr/local/mysql/data/mysql.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

主要配置

# Slave
# 開啓日誌
log-bin = mysql-bin
# 日誌按照行進行數據同步
binlog-format = ROW
# 設置服務id，主從不能一致
server-id = 2
# 設置需要同步的數據庫
replicate-do-db=user_db
# 設置忽略系統庫
replicate-ignore-db = mysql 
replicate-ignore-db = information_schema 
replicate-ignore-db = performance_schema 
replicate-ignore-db = sys

2.4 Master上創建用於主從復置的賬號

mysql -uroot -p123456 -h192.168.124.12

CREATE USER 'sync'@'%' IDENTIFIED WITH mysql_native_password BY '123456';

# 授權主備複製專用賬號
GRANT REPLICATION SLAVE ON *.* TO 'sync'@'%';

show grants for sync;

# 刷新權限
flush privileges;

# 確認位點，記錄下文件名及位點
show master status;

mysql 數據庫中查詢user表獲取文件名和點位

mysql-bin.0000011 156

2.5 Slave上設置從庫向主庫同步

首先切換到從庫登錄

mysql -uroot -p123456 -h192.168.124.11 -P3306

# 先停止同步
stop slave;

# 修改從庫指向到主庫，使用上一步記錄的文件名以及位點
CHANGE MASTER TO 
master_host='192.168.124.12',
master_port=3306,
master_user='sync',
master_password='123456',
master_log_file='mysql-bin.000011',
master_log_pos=156;

# 啓動同步
start slave;

# 查看slave 的狀態
show slave status;

CREATE SCHEMA `testdb` DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci ;

CREATE TABLE `testdb`.`t_user` (
  `id` BIGINT NOT NULL,
  `name` VARCHAR(45) NOT NULL,
  `age` INT NOT NULL,
  PRIMARY KEY (`id`))
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8mb4
COLLATE = utf8mb4_unicode_ci;

INSERT INTO `testdb`.`t_user` (`id`, `name`, `age`) VALUES ('1', 'zhangsan', '3');

需要注意的是數據庫的字符集編碼必須一致

3 ShardingSphere實現讀寫分離

3.1 配置properties

# sharding-JDBC分片策略（主從複製配置）

# 配置數據源，給數據源命名
spring.shardingsphere.datasource.names=m0,s0

# 配置數據源具體內容，連接池、驅動、地址、用戶名和密碼
# testdb 主服務器
spring.shardingsphere.datasource.m0.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.m0.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.m0.url=jdbc:mysql://192.168.124.12:3306/testdb?serverTimezone=GMT%2B8
spring.shardingsphere.datasource.m0.username=root
spring.shardingsphere.datasource.m0.password=123456

# 配置數據源具體內容，連接池、驅動、地址、用戶名和密碼
# testdb 從服務器
spring.shardingsphere.datasource.s0.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.s0.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.s0.url=jdbc:mysql://192.168.124.11:3306/testdb?serverTimezone=GMT%2B8
spring.shardingsphere.datasource.s0.username=root
spring.shardingsphere.datasource.s0.password=123456


# 一個實體類對應兩張表，覆蓋
spring.main.allow-bean-definition-overriding=true

# 主從庫邏輯數據源定義 ds0 爲testdb
spring.shardingsphere.sharding.master-slave-rules.ds0.master-data-source-name=m0
spring.shardingsphere.sharding.master-slave-rules.ds0.slave-data-source-names=s0

# t_user 分表策略，固定分配至ds0的t_user真實表
spring.shardingsphere.sharding.tables.t_user.actual-data-nodes=ds$->{0}.t_user

spring.shardingsphere.sharding.tables.t_user.key-generator.column=id
spring.shardingsphere.sharding.tables.t_user.key-generator.type=SNOWFLAKE

# 打印sql輸出日誌
spring.shardingsphere.props.sql.show=true

3.2 編寫po

package com.ccb.sharding.po;

import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

@TableName("t_user")
public class Student {
    @TableId("id")
    private Long id;
    private String name;
    private int age;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

3.3 編寫mapper

package com.ccb.sharding.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.ccb.sharding.po.Student;
import com.ccb.sharding.po.User;
import org.springframework.stereotype.Repository;

@Repository
public interface StudentMapper extends BaseMapper<Student> {

}

3.4 編寫Test

package com.ccb.sharding;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.ccb.sharding.mapper.StudentMapper;
import com.ccb.sharding.po.Student;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class ShardingApplicationTests {

    @Autowired
    StudentMapper studentMapper;

    // ================= 測試讀寫分離 ======================
    @Test
    public void addStudentMaster() {
        Student student = new Student();
        student.setName("Lily");
        student.setAge(23);
        studentMapper.insert(student);
    }

    @Test
    public void getStudentSlave(){
        QueryWrapper queryWrapper = new QueryWrapper();
        queryWrapper.eq("id",1278468912563892226L);
        Student student = studentMapper.selectOne(queryWrapper);
        System.out.println(student);
    }

}

3.5 TestRest

3.5.1 主庫

3.5.2 從庫

Result

3.5.3 寫入時

3.5.4 讀取時

以上可以看到主從都有數據，並且寫入時是主庫master，讀取時是從庫slave，實現了目標主從複製、讀寫分離