title: Order and limit results in a query with a callback
body: <p>Using Mongoose, I'd like to make a query with MongoDB and order and limit the results I get. I am doing this with Node.js so I am using callbacks.</p>
  
  <p>So far, I have managed to order my results like this:</p>
  
  <pre><code>  myModel.find({ $query: {}, $orderby: { created_at : -1 }}, function (err, items) {
      callback( null, items )
    });  
  </code></pre>
  
  <p>How can I limit the results I get selecting and index and the number of items I want to get?</p>