MySQL 操作命令梳理（3）-pager

 

在mysql日常操作中，妙用pager設置顯示方式，可以大大提高工作效率。比如select出來的結果集超過幾個屏幕，那么前面的結果一晃而過無法看到，這時候使用pager可以設置調用os的more或者less等顯示查詢結果，和在os中使用more或者less查看大文件的效果一樣。

pager用法：
實際上等於將它設置以后的所有mysql操作命令的輸出通過pager設置命令執行，類似於管道符的作用

nopager命令：取消pager設置，恢復之前的輸出狀態。（如果不設置nopager，那么只能通過重啟mysql服務才能恢復了）

舉些例子來說明吧：
1）當處理大量數據時，不想顯示查詢的結果，而只需知道查詢花費的時間。

mysql> select * from huanqiu.haha;
+----+------------+
| id | name       |
+----+------------+
|  1 | wangshibo  |
|  2 | wangshikui |
|  3 | wangjuan   |
|  4 | wangman    |
| 11 | wangshikui |
+----+------------+
5 rows in set (0.00 sec)
mysql> pager cat /dev/null;        //實際上等於后面執行的命令|cat /dev/null，這樣顯示結果就只是執行時間了
PAGER set to 'cat /dev/null'
mysql> select * from huanqiu.haha;  
5 rows in set (0.00 sec)

mysql> nopager;                   //恢復之前的輸出狀態
PAGER set to stdout

mysql> select * from huanqiu.haha;
+----+------------+
| id | name       |
+----+------------+
|  1 | wangshibo  |
|  2 | wangshikui |
|  3 | wangjuan   |
|  4 | wangman    |
| 11 | wangshikui |
+----+------------+
5 rows in set (0.00 sec)

2）如果有大量連接，用show processlist看不方便，想看有多少Sleep狀態，則可以用pager。

mysql> show processlist;
+------+-------+---------------------+--------+-------------+------+-----------------------------------------------------------------------+------------------+
| Id   | User  | Host                | db     | Command     | Time | State                                                                 | Info             |
+------+-------+---------------------+--------+-------------+------+-----------------------------------------------------------------------+------------------+
|    5 | root  | localhost           | huanpc | Query       |    0 | init                                                                  | show processlist |
| 1801 | slave | 192.168.1.102:37125 | NULL   | Binlog Dump | 9904 | Master has sent all binlog to slave; waiting for binlog to be updated | NULL             |
+------+-------+---------------------+--------+-------------+------+-----------------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)

mysql> pager grep Sleep |wc -l;     
PAGER set to 'grep Sleep |wc -l'
mysql> show processlist;           //類似於show processlist結果再通過grep Sleep |wc -l顯示；下面表示一共有2個連接，其中0個Sleep狀態的連接。
0
2 rows in set (0.00 sec)
mysql> nopager;                    //恢復之前的輸出狀態

3）設置pager，只查看slave狀態的幾個status值。

mysql> show slave status \G;              //其中的\G表示顯示要換行顯示
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.101
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000001
          Read_Master_Log_Pos: 5370489
               Relay_Log_File: mysql-relay-bin.000005
                Relay_Log_Pos: 2476520
        Relay_Master_Log_File: mysql-bin.000001
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: huanqiu,huanpc
          Replicate_Ignore_DB: mysql
           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: 5370489
              Relay_Log_Space: 2476693
              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: 101
                  Master_UUID: b667a58f-d6e0-11e6-8c0a-fa163e2d66ac
             Master_Info_File: /data/mysql/data/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)

ERROR: 
No query specified

mysql> pager cat | egrep -i 'system user|Exec_Master_Log_Pos|Seconds_Behind_Master|Read_Master_Log_Pos';
PAGER set to 'cat | egrep -i 'system user|Exec_Master_Log_Pos|Seconds_Behind_Master|Read_Master_Log_Pos''

mysql> show slave status \G;
          Read_Master_Log_Pos: 5370489
          Exec_Master_Log_Pos: 5370489
        Seconds_Behind_Master: 0
1 row in set (0.00 sec)

ERROR: 
No query specified

mysql> nopager;                 //恢復之前的顯示狀態
PAGER set to stdout