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https://issues.apache.org/jira/browse/SPARK-12978?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Reynold Xin updated SPARK-12978:
--------------------------------
    Target Version/s: 2.1.0  (was: 2.0.0)

> Skip unnecessary final group-by when input data already clustered with 
> group-by keys
> ------------------------------------------------------------------------------------
>
>                 Key: SPARK-12978
>                 URL: https://issues.apache.org/jira/browse/SPARK-12978
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 1.6.0
>            Reporter: Takeshi Yamamuro
>
> This ticket targets the optimization to skip an unnecessary group-by 
> operation below;
> Without opt.:
> {code}
> == Physical Plan ==
> TungstenAggregate(key=[col0#159], 
> functions=[(sum(col1#160),mode=Final,isDistinct=false),(avg(col2#161),mode=Final,isDistinct=false)],
>  output=[col0#159,sum(col1)#177,avg(col2)#178])
> +- TungstenAggregate(key=[col0#159], 
> functions=[(sum(col1#160),mode=Partial,isDistinct=false),(avg(col2#161),mode=Partial,isDistinct=false)],
>  output=[col0#159,sum#200,sum#201,count#202L])
>    +- TungstenExchange hashpartitioning(col0#159,200), None
>       +- InMemoryColumnarTableScan [col0#159,col1#160,col2#161], 
> InMemoryRelation [col0#159,col1#160,col2#161], true, 10000, 
> StorageLevel(true, true, false, true, 1), ConvertToUnsafe, None
> {code}
> With opt.:
> {code}
> == Physical Plan ==
> TungstenAggregate(key=[col0#159], 
> functions=[(sum(col1#160),mode=Complete,isDistinct=false),(avg(col2#161),mode=Final,isDistinct=false)],
>  output=[col0#159,sum(col1)#177,avg(col2)#178])
> +- TungstenExchange hashpartitioning(col0#159,200), None
>   +- InMemoryColumnarTableScan [col0#159,col1#160,col2#161], InMemoryRelation 
> [col0#159,col1#160,col2#161], true, 10000, StorageLevel(true, true, false, 
> true, 1), ConvertToUnsafe, None
> {code}



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