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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2014/11/18 22:08:33 UTC
[jira] [Commented] (SPARK-2554) CountDistinct and SumDistinct
should do partial aggregation
[ https://issues.apache.org/jira/browse/SPARK-2554?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14216790#comment-14216790 ]
Apache Spark commented on SPARK-2554:
-------------------------------------
User 'ravipesala' has created a pull request for this issue:
https://github.com/apache/spark/pull/3348
> 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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