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https://issues.apache.org/jira/browse/HIVE-4470?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13720172#comment-13720172
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Gunther Hagleitner commented on HIVE-4470:
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What about Map joins? They can use up a tremendous amount of memory and affect 
the stability if you have multiple concurrent queries, couldn't they? Map join 
local work can also contain UDFs. Disallowing map joins on hive server 2 seems 
bad because of the performance penalty.
                
> HS2 should disable local query execution
> ----------------------------------------
>
>                 Key: HIVE-4470
>                 URL: https://issues.apache.org/jira/browse/HIVE-4470
>             Project: Hive
>          Issue Type: Bug
>          Components: HiveServer2
>            Reporter: Thejas M Nair
>
> Hive can run queries in local mode (instead of using a cluster), if the size 
> is small. This happens when "hive.exec.mode.local.auto" is set to true.
> This would affect the stability of the hive server2 node, if you have heavy 
> query processing happening on it. Bugs in udfs triggered by a bad record can 
> potentially add very heavy load making the server inaccessible. 
> By default, HS2 should set these parameters to disallow local execution or 
> send and error message if user tries to set these.

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