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

["Apache Spark (JIRA)" <ji...@apache.org>]

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

Apache Spark reassigned SPARK-8317:
-----------------------------------

    Assignee: Apache Spark  (was: Josh Rosen)

> 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: Apache Spark
>
> 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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