title: Is it possible to eliminate "empty" facets with Elastic Search?
body: <p>I've finally managed to get Elastic Search indexing to work the way I want it to work, indexing the raw values of certain fields using subfields and <code>not_analyzed</code>. The facets are what I expect, however, in some cases, due to the source data having null/empty values for those fields, I get results like this in the facets section:</p>
  
  <pre><code>  "things": {
       "_type": "terms",
       "missing": 187,
       "total": 12214,
       "other": 10608,
       "terms": [
          {
             "term": "foo",
             "count": 912
          },
          {
             "term": "",
             "count": 532
          },
          {
             "term": "bar",
             "count": 37
          }
       }
    }
  </code></pre>
  
  <p>Note the "" in the second item. I can see why ElasticSearch wouldn't automatically exclude this, as one might want to know how many documents don't have the field. But for my purposes I'd like to just not have this returned.</p>
  
  <p>Is there some way that I can configure ElasticSearch to ignore these, either in the indexing or in the query?</p>