Elastic Search Aggregation

ES Provides aggregated data based on  a search query.

Aggregation Structure:
"aggregations" : {
    "<aggregation_name>" : {
        "<aggregation_type>" : {
            <aggregation_body>
        }
        [,"meta" : {  [<meta_data_body>] } ]?
        [,"aggregations" : { [<sub_aggregation>]+ } ]?
    }
    [,"<aggregation_name_2>" : { ... } ]*
}

#Sub Aggregation; Aggregation can be further refined after adding inner aggregation
#Aggregation_name is a logical name that user defines it.
#aggregation_type is added based on the nature of aggregation. For eg avg_price to calculate average of the price bucket.

GET employees/_search

{

  "_source": false,

  "query": {

    "exists": {

      "field": "employee.address"

    }

  },

  "aggs": { // aggregations

    "address": {

      "terms": {

        "field": "employee_name",

        "size": 500

      }

    }

  }

}

https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics-min-aggregation.html