ElasticSearch: greater between two aggregations -

i'm new elasticsearch , trying greater value between 2 aggregations, possible? need greater between avg_field1 , avg_field2.

i thinking in try use script: max, didn't find example of usage.. don't know if it's possible.

my aggregations now:

{  "aggs" : {    "group_by_frame" : {        "histogram" : {            "field" : "index_histogram",            "interval" : 100        },        "aggs" : {            "avg_field1" : { "avg" : { "field" : "field1" } },            "avg_field2" : { "avg" : { "field" : "field2" } }        }     }  } 

please see answer here: elastic search sum of aggregated values

basically cannot aggregate on different aggregations.