liuyan created HIVE-22157:
-----------------------------

             Summary: Hive Pushing Aggr extension to Druid
                 Key: HIVE-22157
                 URL: https://issues.apache.org/jira/browse/HIVE-22157
             Project: Hive
          Issue Type: Wish
          Components: Druid integration
    Affects Versions: 3.1.2, 3.1.1, 3.1.0, 3.0.0
            Reporter: liuyan


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.  

 

It's we can call Druid's UDAF from HiveSQL and been able push that call into 
the execution plan to use that UDAF on Druid DataSource, this would be a nice 
thing to power up the Hive-Druid Integration.

 



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