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https://issues.apache.org/jira/browse/HIVE-8202?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14169973#comment-14169973
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Xuefu Zhang commented on HIVE-8202:
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Hi [~szehon], thanks for the excellent writeup. I'm wondering if you can
convert the MS doc to pdf and attach it here. Somehow, the open office has
problem displaying the charts in the doc. Thanks.
> Support SMB Join for Hive on Spark [Spark Branch]
> -------------------------------------------------
>
> Key: HIVE-8202
> URL: https://issues.apache.org/jira/browse/HIVE-8202
> Project: Hive
> Issue Type: Sub-task
> Components: Spark
> Reporter: Xuefu Zhang
> Assignee: Szehon Ho
> Attachments: Hive on Spark SMB Join.docx
>
>
> SMB joins are used wherever the tables are sorted and bucketed. It's a
> reduce-side join. The join boils down to just merging the already sorted
> tables, allowing this operation to be faster than an ordinary map-join.
> However, if the tables are partitioned, there could be a slow down as each
> mapper would need to get a very small chunk of a partition which has a single
> key. Thus, in some scenarios it's beneficial to convert SMB join to SMB map
> join as well.
> The task is to research and support the conversion from regular SMB join to
> SMB map join for Spark execution engine.
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