Hive Pushing Aggr extension to Druid

Currently Hive can not push aggr spec if one want to use customized extension in druid for the execution

when using Hive, below query is been rewritten with no aggr defined 

Explain  select  floor_day(`_time`),count(distinct visitor_id) as uv from druid group by floor_day(`_time`);

.....

"limitSpec":{"type":"default"},

"aggregations":[],

"intervals":["1900-01-01T00:00:00.000Z/3000-01-01T00:00:00.000Z"]

...... 

 

But what one really need was 

 

"aggregations": [

{ "type": "distinctCount", "name": "uv", "fieldName": "visitor_id" }

]

 

and aggregations spec is using the druid-distinctcount extension.  

 

If we can call Druid's Native UDAF from HiveSQL and been able push that into the generated Druid query spec, this would be a nice thing to power up the Hive-Druid Integration.