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 |
+---------------+-------+
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。
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