Mysql 5.7 多源复制有个限制，源数据库的名称不能相同。下面测试在两个源主库创建相同数据库test,第二个主库创建的时候查看从库状态报错如下所示：
查看从库进程状态http://www.cndba.cn/cndba/leo1990/article/2720http://www.cndba.cn/cndba/leo1990/article/2720http://www.cndba.cn/cndba/leo1990/article/2720

mysql> SHOW SLAVE STATUS FOR CHANNEL 'Master_2'/G;
...
Last_SQL_Errno: 1007
Last_SQL_Error: Error 'Can't create database 'test'; database exists' on query. Default database: 'test'. Query: 'create database test'
...

错误日志：

2018-04-11T06:31:41.608259Z 14 [Note] Slave SQL thread for channel 'master_2' initialized, starting replication in log 'master2-bin.000004' at position 411, relay log './relay-bin-master_2.000007' position: 628
2018-04-11T06:31:41.608381Z 14 [ERROR] Slave SQL for channel 'master_2': Error 'Can't create database 'test'; database exists' on query. Default database: 'test'. Query: 'create database test', Error_code: 1007
2018-04-11T06:31:41.608402Z 14 [Warning] Slave: Can't create database 'test'; database exists Error_code: 1007
2018-04-11T06:31:41.608410Z 14 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'master2-bin.000004' position 411

解决方法：http://www.cndba.cn/cndba/leo1990/article/2720

mysql> stop slave;
Query OK, 0 rows affected (0.01 sec)
将binglog指针下移一个位置。
mysql>  set GLOBAL SQL_SLAVE_SKIP_COUNTER=1;
Query OK, 0 rows affected (0.00 sec)

mysql> start slave for CHANNEL  'Master_2';
Query OK, 0 rows affected (0.00 sec)

mysql> SHOW SLAVE STATUS FOR CHANNEL 'Master_2'/G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.33
                  Master_User: rep2
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: master2-bin.000004
          Read_Master_Log_Pos: 720
               Relay_Log_File: relay-bin-master_2.000010
                Relay_Log_Pos: 322
        Relay_Master_Log_File: master2-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: 720
              Relay_Log_Space: 700
              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: 33
                  Master_UUID: 73acf59b-3d3c-11e8-b976-080027686323
             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: master_2
           Master_TLS_Version: 
1 row in set (0.00 sec)

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