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https://issues.apache.org/jira/browse/HIVE-10302?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14568202#comment-14568202
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Sergey Shelukhin commented on HIVE-10302:
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Actually I wonder why you guys still work on routine jiras on the branch after
the main merge. Usually branch is reserved for major feature and abandoned
after merge, unless there's some other major feature with epic merge...
> Load small tables (for map join) in executor memory only once [Spark Branch]
> ----------------------------------------------------------------------------
>
> Key: HIVE-10302
> URL: https://issues.apache.org/jira/browse/HIVE-10302
> Project: Hive
> Issue Type: Improvement
> Reporter: Jimmy Xiang
> Assignee: Jimmy Xiang
> Fix For: 1.3.0
>
> Attachments: 10302.patch, HIVE-10302.2-spark.patch,
> HIVE-10302.3-spark.patch, HIVE-10302.4-spark.patch, HIVE-10302.spark-1.patch
>
>
> Usually there are multiple cores in a Spark executor, and thus it's possible
> that multiple map-join tasks can be running in the same executor
> (concurrently or sequentially). Currently, each task will load its own copy
> of the small tables for map join into memory, ending up with inefficiency.
> Ideally, we only load the small tables once and share them among the tasks
> running in that executor.
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