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From "Xuefu Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9561) SHUFFLE_SORT should only be used for order by query [Spark Branch]
Date Fri, 06 Feb 2015 03:45:35 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9561?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14308560#comment-14308560
] 

Xuefu Zhang commented on HIVE-9561:
-----------------------------------

Yeah, hasSortBy and hasOrderBy are for the whole query. Thus, they are not reliable for either
detection. I think we can add a flag in ReduceSinkDesc, similar to enforceSort, telling about
sortBy/orderBy/None.

Yes, I think that optimization makes sense. Please do some prototyping. If all is well, create
an JIRA for it.

> SHUFFLE_SORT should only be used for order by query [Spark Branch]
> ------------------------------------------------------------------
>
>                 Key: HIVE-9561
>                 URL: https://issues.apache.org/jira/browse/HIVE-9561
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Spark
>            Reporter: Rui Li
>            Assignee: Rui Li
>         Attachments: HIVE-9561.1-spark.patch
>
>
> The {{sortByKey}} shuffle launches probe jobs. Such jobs can hurt performance and are
difficult to control. So we should limit the use of {{sortByKey}} to order by query only.



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