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https://issues.apache.org/jira/browse/HIVE-7384?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14105301#comment-14105301
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Lianhui Wang commented on HIVE-7384:
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i think current spark already support hash by join_col,sort by {join_col,tag}.
because in spark map's shuffleWriter hash by Key.hashcode and sort by Key and
in Hive HiveKey class already define the hashcode. so that can support hash by
HiveKey.hashcode, sort by HiveKey's bytes
> Research into reduce-side join [Spark Branch]
> ---------------------------------------------
>
> Key: HIVE-7384
> URL: https://issues.apache.org/jira/browse/HIVE-7384
> Project: Hive
> Issue Type: Sub-task
> Components: Spark
> Reporter: Xuefu Zhang
> Assignee: Szehon Ho
> Attachments: Hive on Spark Reduce Side Join.docx, sales_items.txt,
> sales_products.txt, sales_stores.txt
>
>
> Hive's join operator is very sophisticated, especially for reduce-side join.
> While we expect that other types of join, such as map-side join and SMB
> map-side join, will work out of the box with our design, there may be some
> complication in reduce-side join, which extensively utilizes key tag and
> shuffle behavior. Our design principle prefers to making Hive implementation
> work out of box also, which might requires new functionality from Spark. The
> tasks is to research into this area, identifying requirements for Spark
> community and the work to be done on Hive to make reduce-side join work.
> A design doc might be needed for this. For more information, please refer to
> the overall design doc on wiki.
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