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https://issues.apache.org/jira/browse/HIVE-8639?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14252142#comment-14252142
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Xuefu Zhang commented on HIVE-8639:
-----------------------------------
+1
> 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-8639.2-spark.patch,
> HIVE-8639.3-spark.patch, HIVE-8639.3-spark.patch, HIVE-8639.4-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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