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From "Xuefu Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-10302) Load small tables (for map join) in executor memory only once [Spark Branch]
Date Fri, 24 Apr 2015 01:53:38 GMT

    [ https://issues.apache.org/jira/browse/HIVE-10302?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14510336#comment-14510336
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Xuefu Zhang commented on HIVE-10302:
------------------------------------

+1 pending on test. The above spark related test failures might be related.

> 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: spark-branch
>
>         Attachments: HIVE-10302.2-spark.patch, HIVE-10302.3-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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