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https://issues.apache.org/jira/browse/SPARK-2554?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Armbrust updated SPARK-2554:
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    Target Version/s: 1.3.0  (was: 1.2.0)

> CountDistinct and SumDistinct should do partial aggregation
> -----------------------------------------------------------
>
>                 Key: SPARK-2554
>                 URL: https://issues.apache.org/jira/browse/SPARK-2554
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 1.0.1, 1.0.2
>            Reporter: Cheng Lian
>            Priority: Minor
>
> {{CountDistinct}} and {{SumDistinct}} should first do a partial aggregation 
> and return unique value sets in each partition as partial results. Shuffle IO 
> can be greatly reduced in in cases that there are only a few unique values.



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