【linux】【mysql】mysql主从数据库

系统环境：Centos7

主：192.168.8.162

从：192.168.8.127

前提条件

a.关闭防火墙

systemctl stop firewalld

关闭防火墙开机自启

systemctl disable firewalld

b.关闭selinux

vi /etc/selinux/config

将SELINUX=enforcing改为SELINUX=disabled

设置后需要重启才能生效

本文参考：CSDN“我的小熊不见了”博主，原文链接：https://blog.csdn.net/qq1311256696/article/details/90747435

首先两台数据库安装mysql8.0

1.查看本机是否安装mariadb

rpm -qa|grep mariadb
rpm -e --nodeps 文件名

2.查看是否已经安装了mysql

rpm -qa | grep -i mysql

如果存在则通过 rpm -ev 包名 --nodeps 卸载

再执行 rpm -qa | grep -i mysql 看是否卸载完成

查找mysql文件，使用rm -rf mysql文件路径删除

find / -name mysql

删除配置文档

rm -rf /etc/my.cnf

3.安装mysql8.0的yum源

yum -y install https://dev.mysql.com/get/mysql80-community-release-el7-1.noarch.rpm

执行 yum search mysql 如果出现 mysql-community-server.x86_64 则安装源成功

4.安装mysql8.0

yum -y install mysql-community-server.x86_64

5.启动mysql

systemctl start mysqld

开机自启：systemctl enable mysqld

6.查看mysql版本

mysql -V

7.设置mysql密码

cat /var/log/mysqld.log

!/dChNphO81E mysql随机生成的密码

修改密码

mysqladmin -u root -p password

9.主库配置

创建一个复制用户，授予用户 slave REPLICATION SLAVE权限和REPLICATION CLIENT权限，用于在主从库之间同步数据。

mysql -uroot -p
USE mysql;
CREATE USER slave IDENTIFIED BY 'Slave@123';
GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%';
FLUSH PRIVILEGES;

vi /etc/my.cnf

添加

server-id=162
log-bin=/var/lib/mysql/mysql-bin

重启数据库

systemctl restart mysqld

连接数据库

mysql -uroot -p

查看日志情况

SHOW MASTER STATUS;

记录下File和Position的值

10.从库配置

vi /etc/my.cnf

添加 server-id=127

重启数据库

systemctl restart mysqld

连接数据库

mysql -uroot -p

停止主从

stop slave

从数据连接主数据库：

change master to master_host='192.168.8.162', master_user='slave', master_password='Slave@123', master_port=3306, master_log_file='mysql-bin.000002', master_log_pos= 1013, master_connect_retry=30;

host、user、password、port为主库的ip、用户名和密码、端口
master_log_file为从主库哪个日志读数据即上文中的File
master_log_pos为从哪里开始读即上文中的Position
master_connect_retry为超时重试时间

开始主从

start slave

查看同步状态

show slave status \G;

SlaveIORunning 和 SlaveSQLRunning 都是Yes说明主从复制已经开启。

若 Slave_IO_Running为Connecting可能是mysql8的密码规则问题

主数据库修改slave的密码规则即可：

ALTER USER 'slave'@'%' IDENTIFIED WITH mysql_native_password BY 'Slave@123';

mysql> stop slave;

Query OK,  rows affected (0.00 sec)

mysql> change master to master_host='192.168.8.162', master_user='slave', master_password='Slave@123', master_port=, master_log_file='mysql-bin.000002', master_log_pos= , master_connect_retry=;

Query OK,  rows affected,  warnings (0.01 sec)

mysql> show slave statu \G;

ERROR  (): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'statu' at line

ERROR:

No query specified

mysql> show slave status \G;

*************************** . row ***************************

               Slave_IO_State:

                  Master_Host: 192.168.8.162

                  Master_User: slave

                  Master_Port:

                Connect_Retry:

              Master_Log_File: mysql-bin.

          Read_Master_Log_Pos:

               Relay_Log_File: localhost-relay-bin.

                Relay_Log_Pos:

        Relay_Master_Log_File: mysql-bin.

             Slave_IO_Running: No

            Slave_SQL_Running: No

              Replicate_Do_DB:

          Replicate_Ignore_DB:

           Replicate_Do_Table:

       Replicate_Ignore_Table:

      Replicate_Wild_Do_Table:

  Replicate_Wild_Ignore_Table:

                   Last_Errno:

                   Last_Error:

                 Skip_Counter:

          Exec_Master_Log_Pos:

              Relay_Log_Space:

              Until_Condition: None

               Until_Log_File:

                Until_Log_Pos:

           Master_SSL_Allowed: No

           Master_SSL_CA_File:

           Master_SSL_CA_Path:

              Master_SSL_Cert:

            Master_SSL_Cipher:

               Master_SSL_Key:

        Seconds_Behind_Master: NULL

Master_SSL_Verify_Server_Cert: No

                Last_IO_Errno:

                Last_IO_Error: error connecting to master 'slave@192.168.8.162:3306' - retry-time:  retries:  message: Authentication plugin 'caching_sha2_password' reported error: Authentication requires secure connection.

               Last_SQL_Errno:

               Last_SQL_Error:

  Replicate_Ignore_Server_Ids:

             Master_Server_Id:

                  Master_UUID:

             Master_Info_File: mysql.slave_master_info

                    SQL_Delay:

          SQL_Remaining_Delay: NULL

      Slave_SQL_Running_State:

           Master_Retry_Count:

                  Master_Bind:

      Last_IO_Error_Timestamp:  ::

     Last_SQL_Error_Timestamp:

               Master_SSL_Crl:

           Master_SSL_Crlpath:

           Retrieved_Gtid_Set:

            Executed_Gtid_Set:

                Auto_Position:

         Replicate_Rewrite_DB:

                 Channel_Name:

           Master_TLS_Version:

       Master_public_key_path:

        Get_master_public_key:

            Network_Namespace:

 row in set (0.00 sec)

ERROR:

No query specified

mysql> start slave;

Query OK,  rows affected (0.01 sec)

mysql> show slave status \G;

*************************** . row ***************************

               Slave_IO_State: Waiting for master to send event

                  Master_Host: 192.168.8.162

                  Master_User: slave

                  Master_Port:

                Connect_Retry:

              Master_Log_File: mysql-bin.

          Read_Master_Log_Pos:

               Relay_Log_File: localhost-relay-bin.

                Relay_Log_Pos:

        Relay_Master_Log_File: mysql-bin.

             Slave_IO_Running: Yes

            Slave_SQL_Running: Yes

              Replicate_Do_DB:

          Replicate_Ignore_DB:

           Replicate_Do_Table:

       Replicate_Ignore_Table:

      Replicate_Wild_Do_Table:

  Replicate_Wild_Ignore_Table:

                   Last_Errno:

                   Last_Error:

                 Skip_Counter:

          Exec_Master_Log_Pos:

              Relay_Log_Space:

              Until_Condition: None

               Until_Log_File:

                Until_Log_Pos:

           Master_SSL_Allowed: No

           Master_SSL_CA_File:

           Master_SSL_CA_Path:

              Master_SSL_Cert:

            Master_SSL_Cipher:

               Master_SSL_Key:

        Seconds_Behind_Master:

Master_SSL_Verify_Server_Cert: No

                Last_IO_Errno:

                Last_IO_Error:

               Last_SQL_Errno:

               Last_SQL_Error:

  Replicate_Ignore_Server_Ids:

             Master_Server_Id:

                  Master_UUID: 0d26dbd8-d501-11e9-9f3d-000c29e24dcf

             Master_Info_File: mysql.slave_master_info

                    SQL_Delay:

          SQL_Remaining_Delay: NULL

      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates

           Master_Retry_Count:

                  Master_Bind:

      Last_IO_Error_Timestamp:

     Last_SQL_Error_Timestamp:

               Master_SSL_Crl:

           Master_SSL_Crlpath:

           Retrieved_Gtid_Set:

            Executed_Gtid_Set:

                Auto_Position:

         Replicate_Rewrite_DB:

                 Channel_Name:

           Master_TLS_Version:

       Master_public_key_path:

        Get_master_public_key:

            Network_Namespace:

 row in set (0.00 sec)

ERROR:

No query specified

11.测试主从数据库

主库创建test数据库

create database test;

测试完成！

如果想只同步某一个数据库

可以在主库的my.cnf

添加

binlog-do-db：binlog日志记录哪个db

或者在从库的my.cnf添加

replicate-do-db：需要复制的数据库名

replicate-ignore-db：不需要复制的数据库名