- Enclosing class:
- HiveDruidRules
public static class HiveDruidRules.AggregateExpandDistinctAggregatesDruidRule
extends org.apache.calcite.plan.RelOptRule
This is a simplified version of AggregateExpandDistinctAggregatesRule
The goal of this simplified version is to help pushing single count distinct as multi-phase aggregates.
This is an okay solution before we actually support grouping sets push-down to Druid.
We are limiting it to one Distinct count to avoid expensive cross join and running into issue
https://issues.apache.org/jira/browse/HIVE-19601