• MySQL 操作命令梳理(3)-pager


    在mysql日常操作中,妙用pager设置显示方式,可以大大提高工作效率。比如select出来的结果集超过几个屏幕,那么前面的结果一晃而过无法看到,这时候使用pager可以设置调用os的more或者less等显示查询结果,和在os中使用more或者less查看大文件的效果一样。

    pager用法:
    实际上等于将它设置以后的所有mysql操作命令的输出通过pager设置命令执行,类似于管道符的作用

    nopager命令取消pager设置,恢复之前的输出状态。(如果不设置nopager,那么只能通过重启mysql服务才能恢复了)

    举些例子来说明吧:
    1)当处理大量数据时,不想显示查询的结果,而只需知道查询花费的时间。

    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;        //实际上等于后面执行的命令|cat /dev/null,这样显示结果就只是执行时间了
    PAGER set to 'cat /dev/null'
    mysql> select * from huanqiu.haha;  
    5 rows in set (0.00 sec)
    mysql> nopager; //恢复之前的输出状态 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)如果有大量连接,用show processlist看不方便,想看有多少Sleep状态,则可以用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;           //类似于show processlist结果再通过grep Sleep |wc -l显示;下面表示一共有2个连接,其中0个Sleep状态的连接。
    0
    2 rows in set (0.00 sec)
    mysql> nopager;                    //恢复之前的输出状态
    

    3)设置pager,只查看slave状态的几个status值。

    mysql> show slave status G;              //其中的G表示显示要换行显示
    *************************** 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;                 //恢复之前的显示状态
    PAGER set to stdout
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  • 原文地址:https://www.cnblogs.com/kevingrace/p/6269816.html
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