title: How to retrieve last update time of each document in MongoDB?
body: <p>I would like to know if there is a way to get the last update/modify time of data (i.e documents) in a collection in MongoDB. More clearly, I want to make a query to retrieve all documents updated after a particular time.</p>
  
  <p>Is there any possible ways to retrieve this last modified timestamp in MongoDB? </p>
  
  <p>Note: For newly created documents, I know that we can retrieve the timestamp from the objectId, but for an update, the id is going to be same. Does MongoDB store the last update time for each document anywhere? </p>
  
  <p>I am using morphia as the java driver, so if there is any possible way from morphia, please let me know.</p>