title: Getting "Field data loading is forbidden" when trying to aggregate
body: <p>I'm trying to do a simple unique aggregation, but getting this error:</p>
  
  <pre><code>java.lang.IllegalStateException: Field data loading is forbidden on eid
  </code></pre>
  
  <p>this is my query:</p>
  
  <pre><code>POST /logstash-2016.06.*/Nginx/_search
  {
    "query": {
      "bool": {
        "filter":  [
            {
              "term": { 
                "pid": "1"
              }
            },
            {
              "term": { 
                "cvprogress": "0"
              }
            },
            {
            "range" : {
                "ServerTime" : {
                    "gte" : "2016-06-28T00:00:00"
                }
            }
            }
        ]
      }
    },
      "aggs": {
            "distinct_colors" : {
                "cardinality" : {
                  "field" : "eid"
                }
            }
          }
  
  }
  </code></pre>