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https://issues.apache.org/jira/browse/IMPALA-8097?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17158605#comment-17158605
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Tim Armstrong commented on IMPALA-8097:
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You can always set mt_dop for individual queries that support it - we've
supported it for queries without joins for a long time and that's fine.
I wouldn't recommend setting --unlock_mt_dop=true in production - you're doing
it at your own risk to some extent - we only allowed setting mt_dop *without*
--unlock_mt_dop for queries when it was production ready - i.e. for queries
with joins we allow it in the upcoming Impala 4.0 release, but not earlier
releases - IMPALA-9099. There have been some bugs that we've fixed with joins
and multithreading that would cause problems in a production environment.
--mt_dop_auto_fallback is another option that we added that will automatically
run unsupported queries without multithreading.
> Experimental flag for running all queries with mt_dop
> -----------------------------------------------------
>
> Key: IMPALA-8097
> URL: https://issues.apache.org/jira/browse/IMPALA-8097
> Project: IMPALA
> Issue Type: Sub-task
> Components: Distributed Exec
> Reporter: Tim Armstrong
> Assignee: Tim Armstrong
> Priority: Major
> Fix For: Impala 3.3.0
>
>
> It's possible to execute queries with joins and inserts with mt_dop with some
> small modifications to the Impala code (without the separate join build
> work). This isn't production-ready because of the other subtasks of
> IMPALA-3902 but it would be useful to have an experimental flag for people to
> play around with to test the functionality.
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