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https://issues.apache.org/jira/browse/SPARK-2978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14105128#comment-14105128
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Sandy Ryza commented on SPARK-2978:
-----------------------------------

[~jerryshao], if I understand correctly, ShuffleRDD already supports what's 
needed here, and satisfying that need is independent of whether we sort on the 
map side.  That said, I think the changes you proposed on SPARK-2926 could 
definitely make this more performant, and we would likely see the same 
improvements you benchmarked for sortByKey.

> Provide an MR-style shuffle transformation
> ------------------------------------------
>
>                 Key: SPARK-2978
>                 URL: https://issues.apache.org/jira/browse/SPARK-2978
>             Project: Spark
>          Issue Type: New Feature
>          Components: Spark Core
>            Reporter: Sandy Ryza
>
> For Hive on Spark joins in particular, and for running legacy MR code in 
> general, I think it would be useful to provide a transformation with the 
> semantics of the Hadoop MR shuffle, i.e. one that
> * groups by key: provides (Key, Iterator[Value])
> * within each partition, provides keys in sorted order
> A couple ways that could make sense to expose this:
> * Add a new operator.  "groupAndSortByKey", 
> "groupByKeyAndSortWithinPartition", "hadoopStyleShuffle", maybe?
> * Allow groupByKey to take an ordering param for keys within a partition



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