title: Varnish Sort Querystring Parameter
body: <p>I've got a lot of requests that avoid caching because all of their list permutations are listed, ie:</p>
  
  <pre><code>http://.....&amp;var=a,b,c
  http://.....&amp;var=a,c,b
  http://.....&amp;var=b,a,c
  http://.....&amp;var=b,c,a
  http://.....&amp;var=c,a,b
  http://.....&amp;var=c,b,a
  </code></pre>
  
  <p>Is there a clever way to hash these to the same value? Is the easiest way to sub in the sorted version of the querystring value?</p>