Scriptable Metric Aggregation

[mattweber]

It would be great if we could have a script-based metric aggregation that can
refer to other metric aggregations from within the script. For example, given
the data and query given in this gist:

https://gist.github.com/mattweber/71033b1bf2ebed1afd8e

It would like to be able to do something like the following for a "profit" calculation:

"cost_agg": {
    "filter": {
        "term": {
            "type": "cost"
        }
    },
    "aggs": {
        "cost_sum_agg": {
            "sum": {
                "field": "value"
            }
        }
    }
},
"sale_agg": {
    "filter": {
        "term": {
            "type": "sale"
        }
    },
    "aggs": {
        "sale_sum_agg": {
            "sum": {
                "field": "value"
            }
        }
    }
},
"profit_agg": {
    "metric_script": {
        "script": "sale_agg>sale_sum_agg - cost_agg>cost_sum_agg"
    }
}

So using the data from the gist we would get a response such as:

{
  "key" : "foobar",
  "doc_count" : 4,
  "sale_agg" : {
    "doc_count" : 2,
    "sale_sum_agg" : {
      "value" : 65.48
    }
  },
  "cost_agg" : {
    "doc_count" : 2,
    "cost_sum_agg" : {
      "value" : 24.68
    }
  },
  "profit_agg": {
    "value": 40.80
  }
}

I believe something like this would be possible given the fact that the
the order parameter of a Terms Aggregation can refer to metric sub-aggregation
values. The logic and retrieving the values should be very similar. Exposing
them to a script might be the hard part.

I will look into this further but I wanted to open the issue in case you are
working on similar functionality or have any suggestions for me.

/cc @uboness @jpountz

[uboness]

@mattweber The one thing we have right now in the aggs framework is that each agg is agnostic of other aggs and we'd like to keep it this way. We do have plans to come out with a scriptable metrics agg that will enable you to compute the profit (look at it as a scriptable map/reduce logic)... we'll create a public issue for it soon... I'll keep this one open and once we have the public issue for it will link the two

[mattweber]

That sounds great, thanks for the update!

[mattweber]

@uboness Just pinging to see if there has been any progress toward functionality that would allow this type of aggregation?