MYSQL命令pager推介

时间:2022-07-24
本文章向大家介绍MYSQL命令pager推介，主要内容包括其使用实例、应用技巧、基本知识点总结和需要注意事项，具有一定的参考价值，需要的朋友可以参考一下。

在日常操作MYSQL的工作中，妙用pager设置显示方式，可以很大可能的提高你的效率。例如我们平常有时候通过select查询出的结果非常多，超过好几屏幕，那么前面的结果看不到，整个结果的详细信息没法看全，这时候就可以使用pager调用系统的more或者less等命令显示查询结果了，跟在操作系统上用more和less查看大文件的效果是差不多的。

pager用法: 当设置了pager之后，MYSQL操作的所有命令的输出都会通过pager设置的命令执行，相当于管道符的作用。

当然需要恢复原样的话，利用nopager命令可以取消pager设置，恢复状态；如果你不通过nopager设置的话，那么只能通过重启MYSQL实例才能恢复了。

下面我们介绍几个实际例子:

1、查询大数据表时候，只希望知道查询消耗时间，不需要看到查询结果

mysql> select count(*) from collector_data_num;
+----------+
| count(*) |
+----------+
|  1935236 |
+----------+
1 row 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 ID from collector_data_num;
1935236 rows in set (3.25 sec)
mysql> select * from collector_data_num limit 1;
1 row in set (0.00 sec)mysql> nopager;
PAGER set to stdout
mysql> select ID from collector_data_num limit 1;
+---------------------+
| ID                  |
+---------------------+
| 00053owjtxfTP1qK5TF |
+---------------------+
1 row in set (0.00 sec)mysql>

2、如果有大量连接，想看有多少Sleep状态

mysql> show processlist;
+---------+------------+---------------------+-----------------+-------------+---------+-----------------------------------------------------------------------+------------------+
| Id      | User       | Host                | db              | Command     | Time    | State                                                                 | Info             |
+---------+------------+---------------------+-----------------+-------------+---------+-----------------------------------------------------------------------+------------------+
|       1 | suser | 192.168.0.123:33481  | monitor_db | Sleep       |      16 |                                                                       | NULL             |
|       2 | suser | 192.168.0.123:33480  | monitor_db | Sleep       |      16 |                                                                       | NULL             |
|       3 | suser | 192.168.0.123:33482  | monitor_db | Sleep       |       5 |                                                                       | NULL             |
|      30 | suser | 192.168.0.123:24591   | monitor_db     | Sleep       |    1763 |                                                                       | NULL             |
|      31 | suser | 192.168.0.123:30559  | monitor_db     | Sleep       |    4453 |                                                                       | NULL             |
|    1085 | mysqlab       | 192.168.0.120:51554  | NULL            | Binlog Dump | 1865911 | Master has sent all binlog to slave; waiting for binlog to be updated | NULL             |
|  957112 | suser | 192.168.0.123:36808  | monitor_db     | Sleep       |      43 |                                                                       | NULL             |
| 1235647 | suser | 192.168.0.123:55570   | monitor_db     | Sleep       |       8 |                                                                       | NULL             |
| 1306214 | suser | 192.168.0.123:2004   | monitor_db     | Sleep       |      13 |                                                                       | NULL             |
| 1315396 | suser | 192.168.0.123:65126 | monitor_db     | Sleep       |     138 |                                                                       | NULL             |
| 1321128 | suser | 192.168.0.123:7944  | monitor_db     | Sleep       |       2 |                                                                       | NULL             |
| 1326809 | suser | 192.168.0.123:15931  | monitor_db     | Sleep       |       7 |                                                                       | NULL             |
| 1329587 | suser | 192.168.0.123:19176 | monitor_db     | Sleep       |     138 |                                                                       | NULL             |
| 1330894 | suser | 192.168.0.123:20888 | monitor_db     | Sleep       |       0 |                                                                       | NULL             |
| 1331751 | suser | 192.168.0.123:19211  | monitor_db     | Sleep       |       3 |                                                                       | NULL             |
| 1331988 | suser | 192.168.0.123:22250 | monitor_db     | Sleep       |     138 |                                                                       | NULL             |
| 1332087 | root       | localhost           | NULL            | Query       |       0 | init                                                                  | show processlist |
+---------+------------+---------------------+-----------------+-------------+---------+-----------------------------------------------------------------------+------------------+
17 rows in set (0.04 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17个连接，其中15个Sleep状态的连接。
15
17 rows in set (0.00 sec)mysql> nopager;   # 恢复之前的输出状态
PAGER set to stdout

3、通过设置pager查看Slave的特定几个状态值

mysql> show slave status G;
*************************** 1. row ***************************
              Slave_IO_State: Waiting for master to send event
                 Master_Host: 192.168.0.23
                 Master_User: mysqlab
                 Master_Port: 3306
               Connect_Retry: 60
             Master_Log_File: mysql-bin.000081
         Read_Master_Log_Pos: 342258054
              Relay_Log_File: mysql-relay-bin.000110
               Relay_Log_Pos: 342258217
       Relay_Master_Log_File: mysql-bin.000081
            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: 342258054
             Relay_Log_Space: 342258437
             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: 24
                 Master_UUID: 5392426b-3e15-11e8-b25b-525400d8821f
            Master_Info_File: /data/mysqldata/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> pager cat | egrep -i 'Slave_IO_Running|Slave_SQL_Running|Seconds_Behind_Master';
PAGER set to 'cat | egrep -i 'Slave_IO_Running|Slave_SQL_Running|Seconds_Behind_Master''
mysql> show slave status G;
            Slave_IO_Running: Yes
           Slave_SQL_Running: Yes
       Seconds_Behind_Master: 0
     Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
1 row in set (0.00 sec)mysql> nopager;    # 恢复之前状态
PAGER set to stdout

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