View only last logline from all hosts

Elastic Stack Kibana
3

thanks, but 2 questions arise:

1: Whatever field i use for collapse (fe. host.name) i get :
"reason": "no mapping found for hostname in order to collapse on"
Which fields can i collapse on ?

fe: GET /cmndmetrics/_mapping/field/host.name returns :

    {
      "cmndmetrics" : {
        "mappings" : {
          "host.name" : {
            "full_name" : "host.name",
            "mapping" : {
              "name" : {
                "type" : "text",
                "fields" : {
                  "keyword" : {
                    "type" : "keyword",
                    "ignore_above" : 256
                  }
                }
              }
            }
          }
        }
      }
    }

but:

    GET cmndmetrics/_search
    {
      "size": 1, 
      "query": {
        "match_all": {}
      },
      "collapse": {
        "field": "host.name"
      }
    }

returns error with:

            "reason": {
              "type": "search_context_exception",
              "reason": "unknown type for collapse field `host.name`, only keywords and numbers are accepted"
            }

2: When i get above working in "Dev Tools", i get (long) Json struct.
How can i use this query output to show a listview of all hosts (one line per host) ?
I think i have to be somewhere else than "dev tools" for this ?