title: elasticsearch: extract number from a field
body: <p>I'm using elasticsearch and kibana for storing my logs. 
  Now what I want is to extract a number from a field and store it a new field.</p>
  
  <p>So for instance, having this:</p>
  
  <p><em>accountExist execution time: 1046 ms</em></p>
  
  <p>I would like to extract the number (1046) and see it in a new field in kibana.</p>
  
  <p>Is it possible? how?
  Thanks for the help</p>