title: Redis "nil" or "empty list or set"
body: <p>I'm currently working with redis using "set" structure.</p>
  
  <p>I want to know if it's possible to clean automatically empty "set" ?</p>
  
  <p>Else find a cron/process to clean periodically empty "set"</p>
  
  <hr>
  
  <p><strong>UPDATE:</strong></p>
  
  <p>More generic question, there is a diff (memory usage) between "(nil)" and "(empty list or set)"</p>
  
  <p>example:</p>
  
  <pre><code>sadd x 1
  srem x
  smembers x
  (empty list or set)
  </code></pre>
  
  <p>or</p>
  
  <pre><code>sadd x 1
  del x
  smembers x
  (nil)
  </code></pre>