title: Some fields missing from the kibana “terms” options
body: <p>I have a "message" field which is not appearing in kibana when I select aggregation by "Terms" and open the "Field" drop-down.</p>
  
  <p>Sadly I'm a pre-beginner at ES but I'm guessing it might have something to do with the mappings. Here is the beginning of the result of the query "GET logstash-2017.02.17" (does it have something to do with the "message_field" section?):</p>
  
  <pre><code>{
    "logstash-2017.02.17": {
      "aliases": {},
      "mappings": {
        "_default_": {
          "_all": {
            "enabled": true,
            "norms": false
          },
          "dynamic_templates": [
            {
              "message_field": {
                "path_match": "message",
                "match_mapping_type": "string",
                "mapping": {
                  "norms": false,
                  "type": "text"
                }
              }
            },
            {
              "string_fields": {
                "match": "*",
                "match_mapping_type": "string",
                "mapping": {
                  "fields": {
                    "keyword": {
                      "type": "keyword"
                    }
                  },
                  "norms": false,
                  "type": "text"
                }
              }
            }
          ],
          "properties": {
            "@timestamp": {
              "type": "date",
              "include_in_all": false
            },
  </code></pre>
  
  <p>As you may have guessed the data is all coming in via logstash. In most cases the message field seems to be created by default when you use the logstash grok filter. However I have other logstash pipelines where I specifically assign data to the message field.</p>