Elasticsearch: Return number of buckets for terms aggregation

[Vineeth-Mohan]

In terms aggregation we can limit the number of buckets using the size parameter but then we are not sure how much buckets exist.
Or we will need to do a separate count aggregation to find this.
Kindly return the total number of distinct terms in the response.

[clintongormley]

Hi @Vineeth-Mohan

Each aggregation is intended to be "minimal". If you want to know how many distinct values there are, you can add a value_count aggregation:

GET /_search
{
  "aggs": {
    "top_terms": {
      "terms": {
        "field": "foo"
      }
    },
    "total_terms": {
      "value_count": {
        "field": "foo"
      }
    }
  }
}

See http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-aggregations-metrics-valuecount-aggregation.html#search-aggregations-metrics-valuecount-aggregation

[dsernst]

@clintongormley: For distinct values, I believe you'd need to use a cardinality aggregation, not value_count:

GET /_search
{
  "aggs": {
    "top_terms": {
      "terms": {
        "field": "foo"
      }
    },
    "distinct_terms": {
      "cardinality": {
        "field": "foo"
      }
    }
  }
}