title: How to exclude results with no refferrer in a Kibana (Apache Lucene) query?
body: <p>I'm trying to monitor 404 and 503 errors using Kibana on our service. I'm trying to build a query that will be optimal for other users, so they won't see as much noise in results. I realize my query could be pretty bad as I have no experience with Apache Lucene whatsoever, just trying to figure it out.</p>
  
  <p>Currently the query is this:</p>
  
  <pre><code>(@fields.method:(GET OR POST OR HEAD) AND 
   @fields.response_code:(404 OR 503)) 
  -@fields.agent:(bingbot,msnbot,googlebot,nekstbot,w2gbot,AhrefsBot,ia_archive,facebookexternalhit,AdsBot-Google)
  </code></pre>
  
  <p>I'm having a problem with results that have no refferrer, displaying</p>
  
  <pre><code>@fields.referrer "-"
  </code></pre>
  
  <p>but I don't know how to exclude results with no referrer. How do I do that?</p>