Flink SQL Client中的session window图解

小咪咪 2022-10-29 01:46 188阅读 0赞

flink sql cookbook中的sql语句是:

SELECT  
      userid,
      SESSION_START(log_time, INTERVAL '10' SECOND) AS session_beg,
      SESSION_ROWTIME(log_time, INTERVAL '10' SECOND) AS session_end,
      COUNT(request_line) AS request_cnt
    FROM server_logs
    WHERE status_code = '403'
    GROUP BY 
      userid, 
      SESSION(log_time, INTERVAL '10' SECOND);

session window

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2FwcGxleXVjaGk_size_16_color_FFFFFF_t_70][]

SQL语句详解

<table> 
 <tbody> 
  <tr> 
   <td><strong>SQL语句的各个部分</strong></td> 
   <td style="width:245px;"><strong>解释</strong></td> 
  </tr> 
  <tr> 
   <td>SELECT &nbsp;<br> &nbsp; userid,</td> 
   <td style="width:245px;">选择userid</td> 
  </tr> 
  <tr> 
   <td>SESSION_START(log_time, INTERVAL '10' SECOND) AS session_beg,</td> 
   <td style="width:245px;">session window的起始时间</td> 
  </tr> 
  <tr> 
   <td>&nbsp; SESSION_ROWTIME(log_time, INTERVAL '10' SECOND) AS session_end,</td> 
   <td style="width:245px;">session window的结束时间</td> 
  </tr> 
  <tr> 
   <td> <p>&nbsp; COUNT(request_line) AS request_cnt</p> <p>FROM server_logs<br> WHERE status_code = '403'</p> </td> 
   <td style="width:245px;">用户请求遭遇403的次数统计</td> 
  </tr> 
  <tr> 
   <td> <p>GROUP BY&nbsp;<br> &nbsp; userid,&nbsp;<br> &nbsp; SESSION(log_time, INTERVAL '10' SECOND);</p> </td> 
   <td style="width:245px;"> <p>各个用户(userid)的各个session</p> <p>分开统计(count)，统计结果互不干扰</p> </td> 
  </tr> 
 </tbody> 
</table>

注意SQL中的'10' second必须保持一致，否则SQL会无法运行

运行结果:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2FwcGxleXVjaGk_size_16_color_FFFFFF_t_70 1][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2FwcGxleXVjaGk_size_16_color_FFFFFF_t_70]: /images/20221024/e58732af8a094e55841268d24053cccf.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2FwcGxleXVjaGk_size_16_color_FFFFFF_t_70 1]: /images/20221024/74c5a27e2b1c4f4d99dbfff069c0c434.png