title: Sort by array length
body: <p>How can I sort a query by the number of elements of an array field?</p>
  
  <p>Let say I have records like</p>
  
  <pre><code>{
   title: '',
   author: '',
   votes: [id,id,id]
  }
  </code></pre>
  
  <p>I would like to do sort by the length of the array votes</p>