title: Cloudwatch insights query to group by field
body: <p>Trying to write a cloud watch insights query to concatenate error messages for the same timestamp to be displayed as one row rather than multiple rows in the result.</p>
  
  <p>So far I have tried the below query.</p>
  
  <pre><code>fields @timestamp,concat(@message)
  | filter @message like /(?i)(Exception|error|fail|)/
  | limit 20
  </code></pre>
  
  <p>This displays the results are below.</p>
  
  <pre><code>2019-09-12T12:17:09.803+10:00 12:17:09,720 |-ERROR in A
  2019-09-12T12:17:09.803+10:00 12:17:09,720 |-ERROR in B
  2019-09-12T12:17:09.803+10:00 12:17:09,720 |-ERROR in C
  </code></pre>
  
  <p>I am expecting the below result.</p>
  
  <p>2019-09-12T12:17:09.803+10:00 12:17:09,720 |- ERROR in A -ERROR in B -ERROR in C</p>