title: Compute the difference between two sets (sorted and simple)
body: <p>Is there a way to compute the difference between two <strong>sorted sets</strong> (zset) or do I have to use simple sets for this?</p>
  
  <p>Problem:</p>
  
  <ol>
  <li>Set <strong>F</strong> contains a list of sorted id's (sorted set, full list)</li>
  <li>Set <strong>K</strong> contains a list of id's (simple set, subset of F)</li>
  </ol>
  
  <p>I want to retrieve every entry in <strong>F</strong>, in order, that's not in <strong>K</strong>.</p>
  
  <p>Is this possible using Redis alone or do I have to do the computation on the application? If yes, what is the best way?</p>
  
  <p>EDIT: <a href="http://redis.io/commands/sdiff">SDIFF</a> does not suit this purpose as it doesn't allow sorted sets.</p>