Elasticsearch - aggregations

agg_rate.groovy

doc['exits'].value > 0) ? doc['orders'].value / doc['exits'].value : 0

report.json

{
    "query": {
        "filtered": {
           "query": {"match_all": {}},
           "filter": {"range": {
              "date": {
                 "from": "2014-03-01",
                 "to": "2015-02-28"
              }
           }}
        }
    },
    "aggs": {
        "counts" : {
            "terms": {
                "field": "variant",
                "order": {
                    "exits": "desc"
                }
            },
            "aggs" : {
                "exits" : {
                    "sum" : {"field":"exits"}
                },
                "orders" : {
                    "sum" : {"field" : "orders"}
                },
                "rate" : {
                    "avg" : {"script" : "agg_rate"}
                }
            }
        }
    }
}