title: Can individual fields be set to expire in MongoDB?
body: <p><strong>I would like to know if it is possible to expire individual fields in a document rather than the entire document.</strong></p>
  
  <p>Having read the documentation on <a href="http://docs.mongodb.org/manual/tutorial/expire-data/" rel="noreferrer">TTL Indexes and Expiring Data</a>, it would appear that it is only possible to expire documents based on a field however I would like to confirm.</p>
  
  <p>The background for this question is that I have a Statistics collection with fields for monthly, weekly, daily and hourly statistics in each document.  I could break this up into 4 separate collections such that the documents in each collection could use a different TTL, however I believe this would also mean that I would need to correspondingly break my bulk updates into one bulk update per collection.  I would like to keep the efficiency benefit of one single bulk operation if possible.</p>