mysql 中replication的作用是什么

今天就跟大家聊聊有关mysql 中replication的作用是什么，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。

1. master mysql 中修改/etc/my.cnf 在mysqld下添加如下两行:
log-bin=/var/lib/mysql/mysql-bin.log
server-id=1
#binlog-do-db=DB1
#binlog-do-db=DB2 #如果备份多个，重复设置这个选项即可
2.重启,添加slave replication 用户
GRANT REPLICATION SLAVE ON *.* TO IDENTIFIED BY slave_password;
FLUSH PRIVILEGES;
FLUSH TABLES WITH READ LOCK;
SHOW MASTER STATUS;

+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000001 | 890 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
unlock tables;
记下 file名和binlog的位置.
4.在slave mysql上操作.
编辑从服务器的配置文件：/etc/my.cnf
[mysqld]
#sync data
server-id=2 #注意不能重复
master-host=192.168.100.10
master-user=slave
master-password=slave_password
master-port=3306
master-connect-retry=60
#replicate-do-db=DB1
#replicate-do-db=
5.重启slave mysql .
stop slave;
CHANGE MASTER TO MASTER_HOST=192.168.100.13, MASTER_USER=slave, MASTER_PASSWORD=slave_password, MASTER_LOG_FILE=mysql-bin.000001, MASTER_LOG_POS=890;
start slave;
5.在master mysql上创建数据库测试,从库是否同步.或者show slave statusG 查看
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
两个yes为同步.
补充：
在从服务器上使用show slave statusG
Slave_IO_Running,为No,
则说明IO_THREAD没有启动，请执行start slave io_thread
Slave_SQL_Running为No
则复制出错,查看Last_error字段排除错误后执行start slave sql_thread
查看Slave_IO_State字段空 //复制没有启动
Connecting to master//没有连接上master
Waiting for master to send event//已经连上
主服务器上的相关命令：
show master status
show slave hosts
show logs
show binlog events
purge logs to log_name
purge logs before date
reset master(老版本flush master)
set sql_log_bin=
从服务器上的相关命令:
slave start
slave stop
SLAVE STOP IO_THREAD //此线程把master段的日志写到本地
SLAVE start IO_THREAD
SLAVE STOP SQL_THREAD //此线程把写到本地的日志应用于数据库
SLAVE start SQL_THREAD
reset slave
SET GLOBAL SQL_SLAVE_SKIP_COUNTER
load data from master
show slave status(SUPER,REPLICATION CLIENT)
CHANGE MASTER TO MASTER_HOST=, MASTER_PORT=,MASTER_USER=, MASTER_PASSWORD= //动态改变master信息
PURGE MASTER [before date] 删除master端已同步过的日志