mysql的主从复制

所有的关系型数据库都存在一个通病性能差，在企业中如果用户量特别打，将所有的数据都存放在一台服务器上，其性能时远远达不到要求的。所以需要使用一些手段来解决其性能的问题。
提升性能的方式有向上扩展以及向外扩展
向上扩展(Scale Up):使用更新更好的硬件，但硬件在怎么更新也有其性能的极限。盲目的向上扩展无法结局根本的问题
向外扩展(Scale Out):就是使用多台机器分摊压力来提供服务

主从复制就是拿多个数据库服务器，组合成一个服务器的集合对外共同服务实现性能的提升，逻辑上使用的时对外扩展的方式(Scale out)来提升服务器的性能。

新主机搭建主从复制搭建

服务器类型	ip地址
主	192.168.73.133
从	192.168.73.145

主服务器操作

1.在主服务器上启用二进制日志

[root@localhost ~]# vim /etc/mysql/my.cnf 
log-bin=/data/bin/mysql-bin
binlog-format=row
server-id=1

2.创建二进制日志目录

[root@localhost ~]# mkdir /data/bin
[root@localhost ~]# chown -R mysql.mysql /data/bin

3.重启服务

[root@localhost ~]# service mysqld restart
Restarting mysqld (via systemctl):                         [  OK  ]

4.创建一个用来让从服务器复制数据的账号

MariaDB [(none)]> GRANT REPLICATION SLAVE ON *.* TO repluser@'192.168.73.%' IDENTIFIED BY 'centos';
Query OK, 0 rows affected (0.00 sec)

5.查看主服务器正在使用的二进制日志

MariaDB [(none)]> SHOW MASTER LOGS;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |       515 |    #当前二进制文件及位置需要记录，从服务器设置时需要
+------------------+-----------+
1 row in set (0.00 sec)

从服务器操作

1.修改配置文件

server-id       = 2     #server-id改为和主服务器不同
read-only               #设置为只读
#log-bin=mysql-bin      #将二进制日志关闭

2.启动MySQL服务器

[root@localhost ~]# service mysqld restart
Starting mysqld (via systemctl):                           [  OK  ]

3.关联主服务器

MariaDB [(none)]> CHANGE MASTER TO MASTER_HOST='192.168.73.133',MASTER_USER='repluser',MASTER_PASSWORD='centos',MASTER_PORT=3306,MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=515;
Query OK, 0 rows affected (0.01 sec)

4.查看从服务器状态

MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 192.168.73.133
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 515
               Relay_Log_File: localhost-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: mysql-bin.000001
             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: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 515
              Relay_Log_Space: 256
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           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: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 0
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
                   Using_Gtid: No
                  Gtid_IO_Pos: 
      Replicate_Do_Domain_Ids: 
  Replicate_Ignore_Domain_Ids: 
                Parallel_Mode: conservative
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: 
1 row in set (0.00 sec)

ERROR: No query specified

5.启动线程

MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.00 sec)

测试

在主服务器上导入一个hellodb数据库

[root@localhost ~]# mysql < hellodb_innodb.sql

从服务器上查看是否同步成功

MariaDB [(none)]> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| hellodb            |      #已经有hellodb库
| information_schema |
| mysql              |
| performance_schema |
| test               |
+--------------------+
5 rows in set (0.00 sec)

主服务器已有数据的情况下搭建主从

拥有一台已经有数据的mysql服务器，追加一台从服务器

服务器	IP地址
Master	192.168.73.148
Slave	192.168.73.149

Master中的数据

[root@localhost ~]# mysql -e "SHOW DATABASES;"
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hellodb            |
| mysql              |
| performance_schema |
| test               |
| test1              |
+--------------------+

配置主服务器

1.修改主服务器配置文件

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
log-bin=/data/bin/mysql-bin
binlog-format=row
[root@localhost ~]# systemctl restart mariadb

2.创建复制账号

[root@localhost ~]# mysql -e "GRANT REPLICATION SLAVE ON *.* TO 'repluser'@'192.168.73.%' IDENTIFIED BY 'centos';"

3.备份主节点中的所有数据

[root@localhost ~]# mysqldump -A --single-transaction -F --master-data=1 > /data/all.sql
[root@localhost ~]# vim /data/all.sql

4.将备份数据传送给从节点

[root@localhost ~]# scp /data/all.sql 192.168.73.149:/data

配置从服务器

1.修改配置文件

[root@localhost ~]# vim /etc/my.cnf
[mysqld]
server-id=2
read-only

2.清空MySQL数据库

[root@localhost ~]# rm -rf /var/lib/mysql/*

3.修改备份数据将chang master to 加入文件中

CHANGE MASTER TO
  MASTER_HOST='192.168.73.148',
  MASTER_USER='repluser',
  MASTER_PASSWORD='centos',
  MASTER_PORT=3306,
  MASTER_LOG_FILE='mysql-bin.000005',
  MASTER_LOG_POS=245;

4.启动MySQL服务，并导入备份

[root@localhost ~]# mysql < /data/all.sql

5.查看从节点状态

MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 192.168.73.148
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 245
               Relay_Log_File: mariadb-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: mysql-bin.000005
             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: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 245
              Relay_Log_Space: 245
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           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: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 0
1 row in set (0.00 sec)

6.启动线程

MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.00 sec)

7.再次查看从节点状态，复制的2个线程已经启动

MariaDB [(none)]> SHOW SLAVE STATUS\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.73.148
                  Master_User: repluser
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 245
               Relay_Log_File: mariadb-relay-bin.000002
                Relay_Log_Pos: 529
        Relay_Master_Log_File: mysql-bin.000005
             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: 0
                   Last_Error: 
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 245
              Relay_Log_Space: 825
              Until_Condition: None
               Until_Log_File: 
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File: 
           Master_SSL_CA_Path: 
              Master_SSL_Cert: 
            Master_SSL_Cipher: 
               Master_SSL_Key: 
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 1
1 row in set (0.00 sec)

测试

主节点删test1库

MariaDB [(none)]> DROP DATABASE  test1;
Query OK, 1 row affected (0.01 sec)

从节点查看是否同步

MariaDB [(none)]> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| hellodb            |
| mysql              |
| performance_schema |
| test               |
+--------------------+
5 rows in set (0.00 sec)      #已经没有test1库

(责任编辑：IT)

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