Elasticsearch value_count and cardinality

gistfile1.txt

curl -XDELETE localhost:9200/test

curl -XPUT localhost:9200/test/doc/1 -d '{ "a": "1" }'

curl -XPUT localhost:9200/test/doc/2 -d '{ "a": "1" }'

curl -XPUT localhost:9200/test/doc/3 -d '{ "a": "1" }'

curl -XPOST "localhost:9200/test/_search?search_type=count&pretty" -d '{
  "aggs": {
    "value_count": {
      "value_count": {
        "field": "a"
      }
    },
    "cardinality": {
      "cardinality": {
        "field": "a"
      }
    }
  }
}'

Returns:

{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "hits" : {
    "total" : 3,
    "max_score" : 0.0,
    "hits" : [ ]
  },
  "aggregations" : {
    "value_count" : {
      "value" : 3
    },
    "cardinality" : {
      "value" : 1
    }
  }
}