title: Querying internal array size in MongoDB
body: <p>Consider a MongoDB document in <code>users</code> collection: </p>
  
  <pre><code>{ username : 'Alex', tags: ['C#', 'Java', 'C++'] }
  </code></pre>
  
  <p>Is there any way, to get the length of the <code>tags</code> array from the server side (without passing the tags to the client) ? </p>
  
  <p>Thank you! </p>