主從環境中，從IO程式被停掉

psufnxk2000發表於2015-03-30
主從環境中 ，如果主中的binlog已經被從讀到中繼日誌，但是還沒有被sql應用，這時從庫上的從IO程式停掉了，sql程式仍然會把已經讀到中繼日誌中的內容應用：
也就是說這兩個是獨立的。

例：
在從庫上 
mysql> stop slave SQL_THREAD;
Query OK, 0 rows affected (0.00 sec)


mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.118.161
                  Master_User: song
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: 1.000021
          Read_Master_Log_Pos: 337
               Relay_Log_File: a.000020
                Relay_Log_Pos: 392
        Relay_Master_Log_File: 1.000021
             Slave_IO_Running: Yes
            Slave_SQL_Running: No
              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: 337
              Relay_Log_Space: 706
              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: NULL
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: 2
                  Master_UUID: dab340ff-d2cc-11e4-a6c8-000c292f3ddd
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State:
           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
1 row in set (0.00 sec)

在主上執行：
mysql> create table test(id int);
Query OK, 0 rows affected (0.04 sec)

mysql> insert into test values (1);
Query OK, 1 row affected (0.01 sec)

mysql> insert into test values (2);
Query OK, 1 row affected (0.01 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

在從上檢視
mysql> show slave status \G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.118.161
                  Master_User: song
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: 1.000021
          Read_Master_Log_Pos: 816            --這個值增加了
               Relay_Log_File: a.000020
                Relay_Log_Pos: 392
        Relay_Master_Log_File: 1.000021
             Slave_IO_Running: Yes
            Slave_SQL_Running: No
              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: 337               --這個值沒變，因為sql程式是停著的
              Relay_Log_Space: 1185
              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: NULL
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: 2
                  Master_UUID: dab340ff-d2cc-11e4-a6c8-000c292f3ddd
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State:
           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
1 row in set (0.00 sec)


mysql>
mysql> stop slave IO_THREAD;
Query OK, 0 rows affected (0.01 sec)

mysql> start slave SQL_THREAD;
Query OK, 0 rows affected (0.03 sec)


mysql> SHOW SLAVE STATUS \G
*************************** 1. row ***************************
               Slave_IO_State:
                  Master_Host: 192.168.118.161
                  Master_User: song
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: 1.000021
          Read_Master_Log_Pos: 816
               Relay_Log_File: a.000020
                Relay_Log_Pos: 871
        Relay_Master_Log_File: 1.000021
             Slave_IO_Running: No
            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: 816                --應用了sql
              Relay_Log_Space: 1185
              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: NULL
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: 2
                  Master_UUID: dab340ff-d2cc-11e4-a6c8-000c292f3ddd
             Master_Info_File: /var/lib/mysql/master.info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
           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
1 row in set (0.00 sec)

mysql> select count(*) from test;   --資料已經被同步過來
+----------+
| count(*) |
+----------+
|        2 |
+----------+
1 row in set (0.30 sec)

來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/25099483/viewspace-1479359/，如需轉載，請註明出處，否則將追究法律責任。

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