title: How to modify TTL for a specific documents in mongodb using c# driver
body: <p>I have bunch of documents in mongo db whoes TTL is set to 24 hrs for first time upon receiving the same request again i need to change the TTL to 2 hrs for those documents. </p>
  
  <p>I tried creating Index with Expire After to 24 hrs for the first time but for the second time i need to update the Expire After to 2 hrs ,so dropped the index and recreated with 2 hrs but this will update the entire documents indexes which are with 24 hrs too.</p>