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https://issues.apache.org/jira/browse/SPARK-6026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14338002#comment-14338002
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Aaron Davidson commented on SPARK-6026:
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Interesting -- what was the setup in which you observed this behavior? Perhaps
my intuition on the relative performance at small partitions is incorrect.
> Eliminate the bypassMergeThreshold parameter and associated hash-ish shuffle
> within the Sort shuffle code
> ---------------------------------------------------------------------------------------------------------
>
> Key: SPARK-6026
> URL: https://issues.apache.org/jira/browse/SPARK-6026
> Project: Spark
> Issue Type: Bug
> Affects Versions: 1.3.0
> Reporter: Kay Ousterhout
>
> The bypassMergeThreshold parameter (and associated use of a hash-ish shuffle
> when the number of partitions is less than this) is basically a workaround
> for SparkSQL, because the fact that the sort-based shuffle stores
> non-serialized objects is a deal-breaker for SparkSQL, which re-uses objects.
> Once the sort-based shuffle is changed to store serialized objects, we
> should never be secretly doing hash-ish shuffle even when the user has
> specified to use sort-based shuffle (because of its otherwise worse
> performance).
> [~rxin][~adav], masters of shuffle, it would be helpful to get agreement from
> you on this proposal (and also a sanity check that I've correctly
> characterized the issue).
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