title: AWS Glue Grok Pattern, timestamp with milliseconds
body: <p>I need to define a grok pattern in AWS Glue Classifie to capture the <code>datestamp</code> with milliseconds on the <code>datetime</code> column of file (which is converted as <code>string</code> by AWS Glue Crawler. I used the <code>DATESTAMP_EVENTLOG</code> predefined in AWS Glue and tried to add the milliseconds into the pattern.</p>
  
  <p>Classification: <code>datetime</code></p>
  
  <p>Grok pattern: <code>%{DATESTAMP_EVENTLOG:string}</code></p>
  
  <p>Custom patterns: </p>
  
  <pre><code>MILLISECONDS (\d){3,7}
  DATESTAMP_EVENTLOG %{YEAR}-%{MONTHNUM}-%{MONTHDAY}T%{HOUR}:%{MINUTE}:%{SECOND}.%{MILLISECONDS}
  </code></pre>
  
  <p>I still could not succeed to implement pattern. Any ideas?<a href="https://i.stack.imgur.com/Eg9EH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Eg9EH.png" alt="snapshot of grok"></a></p>