title: Why do we need created_at in MongoDB
body: <p>Why do we when the <code>created_at</code> field when the <code>timestamp</code> can be found in the first 4 bytes of the <code>ObjectId</code> </p>
  
  <pre><code>ObjectId("5349b4ddd2781d08c09890f4").getTimestamp()
  </code></pre>
  
  <p>Taken from <a href="http://www.tutorialspoint.com/mongodb/mongodb_objectid.htm" rel="noreferrer">MongoDB Docs</a></p>