MySQL 主从同步

1.简介

MySQL作为世界上使用最为广泛的数据库之一，免费是其原因之一。但不可忽略的是它本身的功能的确很强大。随着技术的发展，在实际的生产环境中，由单台MySQL数据库服务器不能满足实际的需求。此时数据库集群就很好的解决了这个问题了。采用MySQL分布式集群，能够搭建一个高并发、负载均衡的集群服务器（这篇博客暂时不涉及）。在此之前我们必须要保证每台MySQL服务器里的数据同步。数据同步我们可以通过MySQL内部配置就可以轻松完成，主要有主从复制和主主复制。

主从复制原理

2.环境说明

两台linux虚拟主机
Linux版本CentOS 7.2、MySQL 5.7
ip：192.168.178.198(主)、192.168.178.199(从)

3.主从复制

主服务器开启 log-bin

#log_bin
log-bin=/var/lib/mysql/mysql-bin
server-id=1

从服务器设置server-id

server-id=2

开始构建主从复制

主库操作

mysql> CREATE USER 'repl1'@'%' IDENTIFIED BY '123456';
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl1'@'192.168.178.198' IDENTIFIED BY '123456';
mysql> FLUSH PRIVILEGES;

mysql> SHOW master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000003 |     2723 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

mysql> show master logs;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000001 |      2079 |
| mysql-bin.000002 |       177 |
| mysql-bin.000003 |      2723 |
+------------------+-----------+
3 rows in set (0.00 sec)

mysql> FLUSH TABLE WITH READ LOCK; # 全库读锁

[root@localhost ~]# mysqldump -uroot -p123456 -S /var/lib/mysql/mysql.sock -A -B --events|gzip >/opt/rep.sql.gz #  数据量大

[root@localhost ~]# mysqldump -uroot -p123456 -S /var/lib/mysql/mysql.sock -A -B --events --master-data=2  >/opt/rep.sql

mysql> UNLOCK tables; # 解锁

从库先将主库的全备数据同步

[root@localhost ~]# mysql-uroot -p123456 -S /var/lib/mysql/mysql.sock >/opt/rep.sql

下面进行主从复制

mysql> CHANGE MASTER TO MASTER_HOST='192.168.178.198',MASTER_USER='repl1',MASTER_PASSWORD='123456',MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=2723;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
mysql> START SLAVE;
Query OK, 0 rows affected (0.00 sec)

# 查看 master.info 
root@localhost ~]# cat /var/lib/mysql/master.info
25
mysql-bin.000003
2723
192.168.178.198
repl1
123456
3306
60
0





0
30.000

0

86400


0

查看主从复制是否配置成功, 当看到Slave_IO_Running: YES、Slave_SQL_Running: YES才表明状态正常

mysql> SHOW SLAVE STATUS\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.178.198
                  Master_User: repl1
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000004
          Read_Master_Log_Pos: 154
               Relay_Log_File: localhost-relay-bin.000003
                Relay_Log_Pos: 367
        Relay_Master_Log_File: mysql-bin.000004
             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: 154
              Relay_Log_Space: 744
              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
                  Master_UUID: f6e6d2d0-cae8-11e7-8def-000c29462b91
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind:
      Last_IO_Error_Timestamp:
     Last_SQL_Error_Timestamp:
               Master_SSL_Crl:
           Master_SSL_Crlpath:
           Retrieved_Gtid_Set:
            Executed_Gtid_Set:
                Auto_Position: 0
         Replicate_Rewrite_DB:
                 Channel_Name:
           Master_TLS_Version:
1 row in set (0.00 sec)

ok,现在主从复制的所有操作已经完成了,现在在主库进行数据库操作就会自动同步到从库