title: Keep only n documents in collection - Meteor
body: <p>I want to keep only the latest n documents in my activityFeed collection, in order to speed up the application. I know that I could subscribe only to n activityFeed elements in my iron-router configs, but it is not necessary to keep all the entries.
  How can I do this?
  Do I need to check on every insert, or is there a better way to do this?</p>
  
  <p>Any help would be greatly appreciated.</p>