[GitHub] jihoonson commented on issue #5566: Applying doubleSum over doubleFirst aggregations in nested groupBy fails

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jihoonson commented on issue #5566: Applying doubleSum over doubleFirst aggregations in nested groupBy fails
URL: https://github.com/apache/incubator-druid/issues/5566#issuecomment-409668501
 
 
   > I'm wondering though, if this use-case shouldn't be possible to handle automatically.
   
   @kskalski good point. We can do unless there's some use cases to get the non-finalized values from the inner query. Probably someone wants to compute a sort of custom aggregator on the pairs of <timestamp, first/last value>.
   
   > so I suppose there is some trick / special postprocessing / flag forcing finalization of results.
   
   Yes, there is a query context flag, called `finalize`, to get finalized results. `FinalizeResultsQueryRunner` is the query runner which automatically checks this flag and do some necessary work. In `GroupByStrategyV2.mergeResults()`, the broker sets `finalize` to false to get non-finalized results from historicals. Once it merges all results from historicals, it finalizes the merged results. Please check `ClientQuerySegmentWalker.makeRunner()` and `FluentQueryRunnerBuilder.applyPostMergeDecoration()`.

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