多主一从，也称为多源复制，数据流向：

• 主库1 -> 从库s
• 主库2 -> 从库s
• 主库n -> 从库s

应用场景

• 数据汇总，可将多个主数据库同步汇总到一个从数据库中，方便数据统计分析。
• 读写分离，从库只用于查询，提高数据库整体性能。

部署环境

    注：使用docker部署mysql实例，方便快速搭建演示环境。但本文重点是讲解主从配置，因此简略描述docker环境构建mysql容器实例。

• 数据库：MySQL 5.7.x  （相比5.5，5.6而言，5.7同步性能更好，支持多源复制，可实现多主一从，主从库版本应保证一致）
• 操作系统：CentOS 7.x
• 容器：Docker 17.09.0-ce
• 镜像：mysql:5.7
• 主库300：IP=192.168.10.212; PORT=4300; server-id=300; database=test3; table=user
• 主库400：IP=192.168.10.212; PORT=4400; server-id=400; database=test4; table=user
• 主库500：IP=192.168.10.212; PORT=4500; server-id=500; database=test5; table=user
• 从库10345：IP=192.168.10.212; PORT=4345; server-id=10345; database=test3,test4,test5; table=user

配置约束

• 主从库必须保证网络畅通可访问
• 主库必须开启binlog日志
• 主从库的server-id必须不同

【主库300】操作及配置

配置my.cnf

[client] port = 3306 default-character-set = utf8mb4 [mysql] port = 3306 default-character-set = utf8mb4 [mysqld] ########################## # summary ########################## #bind-address = 0.0.0.0 #port = 3306 #datadir=/datavol/mysql/data #数据存储目录 ########################## # log bin ########################## server-id = 300 #必须唯一 log_bin = mysql-bin #开启及设置二进制日志文件名称 binlog_format = MIXED sync_binlog = 1 expire_logs_days =7 #二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。 #binlog_cache_size = 128m #max_binlog_cache_size = 512m #max_binlog_size = 256M binlog-do-db = test3 #要同步的数据库 binlog-ignore-db = mysql #不需要同步的数据库 binlog_ignore_db = information_schema binlog_ignore_db = performation_schema binlog_ignore_db = sys ########################## # character set ########################## character-set-server = utf8mb4 collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4300:3306 --name=mysql-300 -v /datavol/mysql-300/conf:/etc/mysql/conf.d -v /datavol/mysql-300/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7 5691bac538e646db00273e3cad5b350dbe6cce0bd176346b7eefd9a6f9e3a9ad [root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 5691bac538e6 mysql:5.7 "docker-entrypoint..." 44 seconds ago Up 43 seconds 33060/tcp, 0.0.0.0:4300->3306/tcp mysql-300 [root@localhost ~]# docker exec -it mysql-300 /bin/bash root@5691bac538e6:/# mysql -u root -p Enter password: 

注：若不熟悉docker，可使用传统方式安装mysql，效果相同。

创建授权用户

连接mysql主数据库，键入命令mysql -u root -p，输入密码后登录数据库。创建用户用于从库同步复制，授予复制、同步访问的权限

mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456'; Query OK, 0 rows affected (0.00 sec) 

log_bin是否开启

mysql> show variables like 'log_bin'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | ON | +---------------+-------+ 1 row in set

查看master状态

mysql> show master status \G; *************************** 1. row *************************** File: mysql-bin.000003 Position: 438 Binlog_Do_DB: test3 Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys

【主库400】配置及操作

配置my.cnf

[client] port = 3306 default-character-set = utf8mb4 [mysql] port = 3306 default-character-set = utf8mb4 [mysqld] ########################## # summary ########################## #bind-address = 0.0.0.0 #port = 3306 #datadir=/datavol/mysql/data #数据存储目录 ########################## # log bin ########################## server-id = 400 #必须唯一 log_bin = mysql-bin #开启及设置二进制日志文件名称 binlog_format = MIXED sync_binlog = 1 expire_logs_days =7 #二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。 #binlog_cache_size = 128m #max_binlog_cache_size = 512m #max_binlog_size = 256M binlog-do-db = test4 #要同步的数据库 binlog-ignore-db = mysql #不需要同步的数据库 binlog_ignore_db = information_schema binlog_ignore_db = performation_schema binlog_ignore_db = sys ########################## # character set ########################## character-set-server = utf8mb4 collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4400:3306 --name=mysql-400 -v /datavol/mysql-400/conf:/etc/mysql/conf.d -v /datavol/mysql-400/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7 19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7 [root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 19e93b6d93ca mysql:5.7 "docker-entrypoint..." 4 seconds ago Up 3 seconds 33060/tcp, 0.0.0.0:4400->3306/tcp mysql-400 [root@localhost ~]# docker exec -it mysql-400 /bin/bash root@19e93b6d93ca:/# mysql -u root -p Enter password: 

创建授权用户

创建用户用于从库同步复制，授予复制、同步访问的权限

mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456'; Query OK, 0 rows affected (0.00 sec) 

log_bin是否开启

mysql> show variables like 'log_bin'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | ON | +---------------+-------+ 1 row in set

查看master状态

mysql> show master status \G; *************************** 1. row *************************** File: mysql-bin.000003 Position: 438 Binlog_Do_DB: test4 Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys

【主库500】配置及操作

配置my.cnf

[client] port = 3306 default-character-set = utf8mb4 [mysql] port = 3306 default-character-set = utf8mb4 [mysqld] ########################## # summary ########################## #bind-address = 0.0.0.0 #port = 3306 #datadir=/datavol/mysql/data #数据存储目录 ########################## # log bin ########################## server-id = 500 #必须唯一 log_bin = mysql-bin #开启及设置二进制日志文件名称 binlog_format = MIXED sync_binlog = 1 expire_logs_days =7 #二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。 #binlog_cache_size = 128m #max_binlog_cache_size = 512m #max_binlog_size = 256M binlog-do-db = test5 #要同步的数据库 binlog-ignore-db = mysql #不需要同步的数据库 binlog_ignore_db = information_schema binlog_ignore_db = performation_schema binlog_ignore_db = sys ########################## # character set ########################## character-set-server = utf8mb4 collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4500:3306 --name=mysql-500 -v /datavol/mysql-500/conf:/etc/mysql/conf.d -v /datavol/mysql-500/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7 19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7 [root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 19e93b6d93ca mysql:5.7 "docker-entrypoint..." 4 seconds ago Up 3 seconds 33060/tcp, 0.0.0.0:4500->3306/tcp mysql-500 [root@localhost ~]# docker exec -it mysql-500 /bin/bash root@19e93b6d93ca:/# mysql -u root -p Enter password: 

创建授权用户

创建用户用于从库同步复制，授予复制、同步访问的权限

mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456'; Query OK, 0 rows affected (0.00 sec) 

log_bin是否开启

mysql> show variables like 'log_bin'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_bin | ON | +---------------+-------+ 1 row in set

查看master状态

mysql> show master status \G; *************************** 1. row *************************** File: mysql-bin.000003 Position: 438 Binlog_Do_DB: test5 Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys

【从库10345】配置及操作

配置my.cnf

[client] port = 3306 default-character-set = utf8mb4 [mysql] port = 3306 default-character-set = utf8mb4 [mysqld] ########################## # summary ########################## #bind-address = 0.0.0.0 #port = 3306 #datadir=/datavol/mysql/data #数据存储目录 ########################## # log bin ########################## server-id = 10345 master_info_repository = table relay_log_info_repository = table ########################## # character set ########################## character-set-server = utf8mb4 collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4345:3306 --name=mysql-10345 -v /datavol/mysql-10345/conf:/etc/mysql/conf.d -v /datavol/mysql-10345/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7 19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7 [root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 19e93b6d93ca mysql:5.7 "docker-entrypoint..." 4 seconds ago Up 3 seconds 33060/tcp, 0.0.0.0:4345->3306/tcp mysql-10345 [root@localhost ~]# docker exec -it mysql-10345 /bin/bash root@19e93b6d93ca:/# mysql -u root -p Enter password: 

设置【主库】信息

登录【从库10345】，进入mysql命令行。

mysql> stop slave; Query OK, 0 rows affected mysql> CHANGE MASTER TO MASTER_HOST='192.168.10.212', MASTER_PORT=4300, MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000003', MASTER_LOG_POS=438 for channel '300'; Query OK, 0 rows affected mysql> CHANGE MASTER TO MASTER_HOST='192.168.10.212', MASTER_PORT=4400, MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000003', MASTER_LOG_POS=438 for channel '400'; Query OK, 0 rows affected mysql> CHANGE MASTER TO MASTER_HOST='192.168.10.212', MASTER_PORT=4500, MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000003', MASTER_LOG_POS=438 for channel '500'; Query OK, 0 rows affected mysql> start slave; Query OK, 0 rows affected

stop slave;     //停止同步
start slave;     //开始同步
//必须和【主库】的信息匹配。
CHANGE MASTER TO
MASTER_HOST='192.168.10.212',     //主库IP
MASTER_PORT=4300,                       //主库端口
MASTER_USER='slave',                     //访问主库且有同步复制权限的用户
MASTER_PASSWORD='123456',      //登录密码
//【关键处】从主库的该log_bin文件开始读取同步信息，主库show master status返回结果
MASTER_LOG_FILE='mysql-bin.000003',
//【关键处】从文件中指定位置开始读取，主库show master status返回结果
MASTER_LOG_POS=438
for channel '300';            //定义通道名称

查看同步状态

mysql> show slave status \G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.10.212 Master_User: slave Master_Port: 4300 Connect_Retry: 60 Master_Log_File: mysql-bin.000003 Read_Master_Log_Pos: 1860 Relay_Log_File: 0ad84f013600-relay-bin-300.000002 Relay_Log_Pos: 1742 Relay_Master_Log_File: mysql-bin.000003 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: 1860 Relay_Log_Space: 1960 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: 300 Master_UUID: 4efae154-ebd4-11e8-bf7d-0242ac110007 Master_Info_File: mysql.slave_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: 300 Master_TLS_Version: *************************** 2. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.10.212 Master_User: slave Master_Port: 4400 Connect_Retry: 60 Master_Log_File: mysql-bin.000003 Read_Master_Log_Pos: 2461 Relay_Log_File: 0ad84f013600-relay-bin-400.000002 Relay_Log_Pos: 1187 Relay_Master_Log_File: mysql-bin.000003 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: 2461 Relay_Log_Space: 1405 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: 400 Master_UUID: 8fb0aa81-ebd4-11e8-ac5b-0242ac110009 Master_Info_File: mysql.slave_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: 400 Master_TLS_Version: *************************** 3. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.10.212 Master_User: slave Master_Port: 4500 Connect_Retry: 60 Master_Log_File: mysql-bin.000003 Read_Master_Log_Pos: 2151 Relay_Log_File: 0ad84f013600-relay-bin-500.000002 Relay_Log_Pos: 626 Relay_Master_Log_File: mysql-bin.000003 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: 2151 Relay_Log_Space: 844 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: 500 Master_UUID: b87704d2-ebd5-11e8-a90c-0242ac11000a Master_Info_File: mysql.slave_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: 500 Master_TLS_Version: 3 rows in set (0.00 sec) 

可以看见设置三个的主从同步通道的所有状态信息。
只有【Slave_IO_Running】和【Slave_SQL_Running】都是Yes，则同步是正常的。
如果是No或者Connecting都不行，可查看mysql-error.log，以排查问题。

mysql> show variables like 'log_error%'; +---------------------+--------+ | Variable_name | Value | +---------------------+--------+ | log_error | stderr | | log_error_verbosity | 3 | +---------------------+--------+ 2 rows in set

配置完成，则【从库10345】开始自动同步。

若需要单独启动或停止某个同步通道，可使用如下命令：
start slave for channel '300';     //启动名称为300的同步通道
stop slave for channel '300';     //停止名称为300的同步通道

验证数据同步

建库

使用root账号登录【主库300】，创建test3数据库 

mysql> CREATE DATABASE test3; Query OK, 1 row affected (0.00 sec) mysql> USE test3; Database changed 

建表

在【主库300】中创建user表

CREATE TABLE `user` (   `id` bigint(20) NOT NULL AUTO_INCREMENT,   `name` varchar(20) COLLATE utf8mb4_unicode_ci NOT NULL,   `age` tinyint(3) unsigned NOT NULL,   PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci; 

新增

在【主库300】中向user表插入一条数据：

mysql> use test3; Database changed mysql> INSERT INTO user (id, name, age) VALUES (300, 'Tom', 18); Database changed mysql> SELECT * FROM user; +-----+------+-----+ | id | name | age | +-----+------+-----+ | 300 | Tom | 18 | +-----+------+-----+ 1 row in set (0.00 sec)

在【从库10345】中查询user表数据：

mysql> use test3; Database changed mysql> SELECT * FROM user; +-----+------+-----+ | id | name | age | +-----+------+-----+ | 300 | Tom | 18 | +-----+------+-----+ 1 row in set (0.00 sec) 

新增记录同步成功。

更新

在【主库300】中修改刚才插入的数据：

mysql> UPDATE user SET name='Peter' where id=300; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from user; +-----+-------+-----+ | id | name | age | +-----+-------+-----+ | 300 | Peter | 18 | +-----+-------+-----+ 1 row in set (0.00 sec)

在【从库10345】中查询user表数据：

mysql> select * from user; +-----+-------+-----+ | id | name | age | +-----+-------+-----+ | 300 | Peter | 18 | +-----+-------+-----+ 1 row in set (0.00 sec)

更新记录同步成功。

删除

在【主库300】中删除刚才更新的数据：

mysql> DELETE FROM user WHERE id=300; Query OK, 1 row affected (0.00 sec) mysql> select * from user; Empty set (0.00 sec)

在【从库10345】中查询user表数据：

mysql> select * from user; Empty set (0.00 sec)

删除记录同步成功。
注：【主库400】、【主库500】的验证操作与上述类似。

补充：

• 如果【主服务器】重启mysql服务，【从服务器】会等待与【主服务器】重连。当主服务器恢复正常后，从服务器会自动重新连接上主服务器，并正常同步数据。
• 如果某段时间内，【从数据库】服务器异常导致同步中断（可能是同步点位置不匹配），可以尝试以下恢复方法：进入【主数据库】服务器（正常），在bin-log中找到【从数据库】出错前的position，然后在【从数据库】上执行change master，将master_log_file和master_log_pos重新指定后，开始同步。