一.从库执行：show slave status\G;
admin@a8-dba-cloud-db00.wh ((none)) > show slave status\G; *************************** 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