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https://issues.apache.org/jira/browse/SPARK-39893?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wan Kun updated SPARK-39893:
----------------------------
    Summary: Remove redundant aggregate if it is group only and all grouping 
and aggregate expressions are foldable  (was: Remove Aggregate if it is group 
only and all grouping and aggregate expressions are foldable)

> Remove redundant aggregate if it is group only and all grouping and aggregate 
> expressions are foldable
> ------------------------------------------------------------------------------------------------------
>
>                 Key: SPARK-39893
>                 URL: https://issues.apache.org/jira/browse/SPARK-39893
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.4.0
>            Reporter: Wan Kun
>            Priority: Major
>
> If all groupingExpressions and aggregateExpressions in a aggregate are 
> foldable, we can remove this aggregate.
> For example, query : 
> {code:java}
> SELECT distinct 1001 as id , cast('2022-06-03' as date) AS DT FROM testData
> {code}
> the grouping expressions are : *[1001, 2022-06-03]*
> the aggregate expressions are :  *[1001 AS id#274, 2022-06-03 AS DT#275]*
> so we can skip scan table testData and remote the aggregate operation.
> Before this PR:
> {code:java}
> Aggregate [1001, 2022-06-03], [1001 AS id#274, 2022-06-03 AS DT#275], 
> Statistics(sizeInBytes=16.0 EiB)
> +- SerializeFromObject, Statistics(sizeInBytes=8.0 EiB)
>    +- ExternalRDD [obj#12], Statistics(sizeInBytes=8.0 EiB)
> {code}
> After this PR:
> {code:java}
> Project [1001 AS id#218, 2022-06-03 AS DT#219], Statistics(sizeInBytes=2.0 B)
> +- OneRowRelation, Statistics(sizeInBytes=1.0 B)
> {code}



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