[jira] [Resolved] (SPARK-8317) Do not push sort into shuffle in Exchange operator

["Michael Armbrust (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-8317?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Michael Armbrust resolved SPARK-8317.
-------------------------------------
       Resolution: Fixed
    Fix Version/s: 1.5.0

Issue resolved by pull request 6772
[https://github.com/apache/spark/pull/6772]

> Do not push sort into shuffle in Exchange operator
> --------------------------------------------------
>
>                 Key: SPARK-8317
>                 URL: https://issues.apache.org/jira/browse/SPARK-8317
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Josh Rosen
>            Assignee: Josh Rosen
>             Fix For: 1.5.0
>
>
> In some cases, Spark SQL pushes sorting operations into the shuffle layer by specifying a key ordering as part of the shuffle dependency. I think that we should not do this:
> - Since we do not delegate aggregation to Spark's shuffle, specifying the keyOrdering as part of the shuffle has no effect on the shuffle map side.
> - By performing the shuffle ourselves (by inserting a sort operator after the shuffle instead), we can use the Exchange planner to choose specialized sorting implementations based on the types of rows being sorted.
> - We can remove some complexity from SqlSerializer2 by not requiring it to know about sort orderings, since SQL's own sort operators will already perform the necessary defensive copying.



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