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From "Jimmy Xiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-8639) Convert SMBJoin to MapJoin [Spark Branch]
Date Thu, 11 Dec 2014 18:07:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-8639?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14242858#comment-14242858
] 

Jimmy Xiang commented on HIVE-8639:
-----------------------------------

[~szehon], looked into the auto_sortmerge_join_9 failure. It is a bug. I filed HIVE-9081.
Thanks.

> Convert SMBJoin to MapJoin [Spark Branch]
> -----------------------------------------
>
>                 Key: HIVE-8639
>                 URL: https://issues.apache.org/jira/browse/HIVE-8639
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Spark
>    Affects Versions: spark-branch
>            Reporter: Szehon Ho
>            Assignee: Szehon Ho
>         Attachments: HIVE-8639.1-spark.patch
>
>
> HIVE-8202 supports auto-conversion of SMB 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 map
join.
> The task is to research and support the conversion from SMB join to map join for Spark
execution engine.  See the equivalent of MapReduce in SortMergeJoinResolver.



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