title: Rails Delete DB Records except for the 10 latest entries
body: <p>I've created a Model called "PostView". Each time a user views a post, it logs it into the database (creating a new record with the user id and post id).</p>
  
  <p>I'm only wanting to retain 10 records per user in the DB. So each time a new record is added, I want to remove all but the latest 10 records.</p>
  
  <ol>
  <li>Is this efficient? If not, what do you suggest as a way to log user/post views?</li>
  <li>How can I add the new record and delete all but the latest 10 records in Rails?</li>
  </ol>
  
  <p>Thanks!</p>