MySql复制的优点：
1.如果主服务器出现问题，可以快速切换到从服务器提供的服务
2.可以在从服务器上执行查询操作，降低主服务器的访问压力
3.可以在从服务器上执行备份，以避免备份期间影响主服务器的服务
注意：一般只有更新不频繁的数据或者对实时性要求不高的数据可以通过从服务器查询，实时性要求高的数据仍然需要从主服务器获得。
1、测试环境
操作系统 ：Windows 7 32位操作系统（安装双数据库端口分别为3306、3308）
数据库版本：MySQL 5.7.18
主机A：192.168.1.103 （Master）
主机B：192.168.1.103（Slave）
配置的设置同样适用于Centos，Centos的配置文件/etc/my.cnf
service mysqld stop #停止数据库
service mysqld start #启动数据库
service mysqld restart #重启数据库
2、数据库安装
可以参考之前写的文章：安装MySql并修改初始密码
这里贴一下Slave数据库安装的日志
Microsoft Windows [版本 6.1.7601]
版权所有 (c) 2009 Microsoft Corporation。保留所有权利。
C:\Windows\system32>cd C:\Program Files\mysql-5.7.18-win32-slave\bin
C:\Program Files\mysql-5.7.18-win32-slave\bin>mysqld --initialize
C:\Program Files\mysql-5.7.18-win32-slave\bin>cd ../data
C:\Program Files\mysql-5.7.18-win32-slave\data>TYPE Javen-PC.err
2017-06-29T02:41:51.068120Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is
deprecated. Please use --explicit_defaults_for_timestamp server option (see doc
umentation for more details).
2017-06-29T02:41:51.573560Z 0 [Warning] InnoDB: New log files created, LSN=45790
2017-06-29T02:41:51.643760Z 0 [Warning] InnoDB: Creating foreign key constraint
system tables.
2017-06-29T02:41:51.699920Z 0 [Warning] No existing UUID has been found, so we a
ssume that this is the first time that this server has been started. Generating
a new UUID: 818f5c2f-5c74-11e7-8dff-000c29b2597f.
2017-06-29T02:41:51.699920Z 0 [Warning] Gtid table is not ready to be used. Tabl
e 'mysql.gtid_executed' cannot be opened.
2017-06-29T02:41:51.713960Z 1 [Note] A temporary password is generated for root@
localhost: =rc%=eBVg0AY
C:\Program Files\mysql-5.7.18-win32-slave\data>cd ..
C:\Program Files\mysql-5.7.18-win32-slave>cd bin
C:\Program Files\mysql-5.7.18-win32-slave\bin>mysqld -install MySQL2
Service successfully installed.
C:\Program Files\mysql-5.7.18-win32-slave\bin>net start MySQL2
MySQL2 服务正在启动 .
MySQL2 服务已经启动成功。
C:\Program Files\mysql-5.7.18-win32-slave\bin>mysql -u root -p=rc%=eBVg0AY -P3308
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.18
Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'root';
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'root' WITH GRANT
OPTION;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
mysql> exit
Bye
1、在mysql-5.7.18-win32-slave根目录中创建my.ini初始化配置文件
[mysqld]
# set basedir to your installation path
basedir=C:\\Program Files\\mysql-5.7.18-win32-slave
# set datadir to the location of your data directory
datadir=C:\\Program Files\\mysql-5.7.18-win32-slave\\data
port = 3308
2、进入bin目录mysqld –initialize初始化数据库文件
3、TYPE Javen-PC.err 查看处理初始化密码。Javen-PC.err 是你电脑的名称 ，这里的初始化密码为=rc%=eBVg0AY
4、注册mysql服务 mysqld -install MySQL2
5、启动服务net start MySQL2
6、登录本地mysql：mysql -u root -p=rc%=eBVg0AY -P3308
7、修改本地root用户密码
ALTER USER 'root'@'localhost' IDENTIFIED BY 'root';
8、授权远程登录(需要关闭防火墙或者配置指定端口可以访问)
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'root' WITH GRANT OPTION;
FLUSH PRIVILEGES;
3、配置主服务器Master
3.1 给从服务器设置授权用户(创建复制帐号)
建立一个帐户javen，并且只能允许从192.168.1.103这个地址上来登陆，密码是123456。
mysql> grant replication slave on *.* to 'javen'@'192.168.1.103' identified by '123456';
mysql> flush privileges;
3.2 主服务器Master配置
[mysqld]
basedir=C:\\Program Files\\mysql-5.7.18-win32
datadir=C:\\Program Files\\mysql-5.7.18-win32\\data
port = 3306
log-bin = mysql-bin
server-id = 1
expire-logs-days = 7
binlog-ignore-db = mysql
binlog-ignore-db = information_schema
binlog-ignore-db = performation_schema
binlog-ignore-db = sys
3.3 重启MySQL服务并设置读取锁定
net stop MySQL
net start MySQL
在主服务器上设置读取锁定有效，确保没有数据库操作，以便获得一个一致性的快照
mysql -u root -proot -P3306
mysql> flush tables with read lock;
3.4 查看主服务器上当前的二进制日志名和偏移量值
----------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB
----------------+-------------------+
| mysql-bin.000001 | 2519 | | mysql,information_schema,performa
tion_schema,sys | |
1 row in set (0.00 sec)
这里的 File 、Position 是在配置Salve的时候要使用到的，Binlog_Do_DB表示要同步的数据库，Binlog_Ignore_DB 表示Ignore的数据库，这些都是在配置的时候进行指定的。
另外：如果执行这个步骤始终为Empty set(0.00 sec)，那说明前面的my.init没配置对。
4、配置从服务器Slave
4.1 修改从数据库的配置
[mysqld]
# set basedir to your installation path
basedir=C:\\Program Files\\mysql-5.7.18-win32-slave
# set datadir to the location of your data directory
datadir=C:\\Program Files\\mysql-5.7.18-win32-slave\\data
port = 3308
log-bin=mysql-bin
server-id=3
binlog-ignore-db = mysql #不备份的数据库
binlog-ignore-db = information_schema
binlog-ignore-db = performation_schema
binlog-ignore-db = sys
log-slave-updates
slave-skip-errors=all
slave-net-timeout=60
4.2 重启从数据库并设置Slave数据库
net stop MySQL2
net start MySQL2
登录从数据库并做如下设置
mysql> stop slave;
mysql> change master to master_host='192.168.1.103',master_user='javen',master_password='123456',master_log_file='mysql-bin.000001', master_log_pos= 2519;
mysql> start slave;
注意：在这里指定Master的信息，master_log_file是在配置Master的时候的File选项， master_log_pos是在配置Master的Position 选项，这里要进行对应。
4.3 查看Slave配置的信息
show slave status 查看配置的信息：
mysql> show slave status \G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.103
Master_User: mysync
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 1192
Relay_Log_File: Javen-PC-relay-bin.000002
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: mysql
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: 1192
Relay_Log_Space: 530
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: 818f5c2f-5c74-11e7-8dff-000c29b2597f
Master_Info_File: C:\Program Files\mysql-5.7.18-win32-slave\data\ma
ster.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more up
dates
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)
ERROR:
No query specified
mysql>
5、关闭掉主数据库的读取锁定
mysql> unlock tables;
6、在主数据库中创建一个表以及添加数据测试
在主数据库（Master）添加一个test数据库并在其中添加t1的数据表。如下图
在从数据库（Slave）自动同步，如下图
如有问题欢迎留言….
在阿里云Centos7.6上面配置Mysql主从数据库(master/slave)，实现读写分离
