title: MongoDB query to distinct, sort, limit and offset
body: <p>I'm looking for a Mongo equivalent of the following:</p>
  
  <pre><code>select distinct event_type_id from events
  order by created_at desc
  limit 10,20
  </code></pre>
  
  <p>The Event Mongo document is as follows:</p>
  
  <pre><code>{
    _id: BSON(), event_type_id: 1, created_at: Date(), other_data: {}
  }
  </code></pre>