跨库复制

一.从库执行：show slave statusG;

admin@a8-dba-cloud-db00.wh ((none)) > show slave statusG;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 10.10.10.10
                  Master_User: mysqlsync
                  Master_Port: 3307
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 3543191
               Relay_Log_File: relay-bin.000002
                Relay_Log_Pos: 3543396
        Relay_Master_Log_File: mysql-bin.000001
             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: 3543191
              Relay_Log_Space: 3543589
              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: 176689962
                  Master_UUID: 978aaabd-82b2-11ea-b0b5-e4434bac7bda
             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: 978aaabd-82b2-11ea-b0b5-e4434bac7bda:1-3692
            Executed_Gtid_Set: 978aaabd-82b2-11ea-b0b5-e4434bac7bda:1-3692
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

ERROR: 
No query specified

Sat May  2 00:58:24 2020

二.现象

使用replicate_do_db和replicate_ignore_db时有一个隐患，跨库更新时会出错。

如设置 replicate_do_db=test
use mysql;
update test.table1 set ......
第二句将不会被执行

如设置 replicate_ignore_db=mysql
use mysql;
update test.table1 set ......
第二句会被忽略执行

原因是设置replicate_do_db或replicate_ignore_db后，MySQL执行sql前检查的是当前默认数据库，所以跨库更新语句被忽略。

可以使用 replicate_wild_do_table 和 replicate_wild_ignore_table 来解决跨库更新的问题，如：
replicate_wild_do_table=test.%
或
replicate_wild_ignore_table=mysql.%

这样就可以避免出现上述问题了