title: Delete documents by date comparison between sum of date and numeric fields and current timestamp
body: <p>The documents in the MongoDB collection have the following schema (showing only relevant fields):</p>
  
  <pre><code>{
      "TTLinSeconds" : 1800,
      "lastUpdatedTimestamp" : ISODate("...")
  }
  </code></pre>
  
  <p>I need to delete all documents where <code>current timestamp</code> is greater than <code>lastUpdatedTimestamp</code> plus the value stored in the <code>TTLinSeconds</code> field. Thanks in advance for your suggestions.</p>