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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2015/07/22 06:29:05 UTC

[jira] [Commented] (SPARK-4367) Partial aggregation support the DISTINCT aggregation

    [ https://issues.apache.org/jira/browse/SPARK-4367?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14636198#comment-14636198 ] 

Apache Spark commented on SPARK-4367:
-------------------------------------

User 'yhuai' has created a pull request for this issue:
https://github.com/apache/spark/pull/7458

> Partial aggregation support the DISTINCT aggregation
> ----------------------------------------------------
>
>                 Key: SPARK-4367
>                 URL: https://issues.apache.org/jira/browse/SPARK-4367
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Cheng Hao
>
> Most of aggregate function(e.g average) with "distinct" value will requires all of the records in the same group to be shuffled into a single node, however, as part of the optimization, those records can be partially aggregated before shuffling, that probably reduces the overhead of shuffling significantly. 



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