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https://issues.apache.org/jira/browse/HIVE-11684?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14740519#comment-14740519
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Jesus Camacho Rodriguez commented on HIVE-11684:
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[~sershe], QA fails are not related to the patch, it is just pending review, so
it should go in soon; this work is done on master.
{quote}
Actually, I wonder if some CBO features should be disable-able via configs,
like existing Hive optimizations. Should I file a JIRA for that?
{quote}
I don't know if we want to go in that direction in the long term, but maybe in
the short term we could do that instead of disabling CBO by default for these
cases. [~jpullokkaran], what's your take on that?
IMO, we should be able to recognize automatically these cases instead of
introducing more config parameters: if we can match a certain criteria e.g.
query with 2 joins whose selectivity is very similar, do not fire up certain
logic in CBO (join reordering, or maybe some other rules). In fact, it would be
necessary to combine static (query) with dynamic (data) information in order to
make these decisions accurately. At the same time, the logic should be
lightweight enough to not add much more overhead to the planning phase,
otherwise it would be cheaper to run the complete CBO path...
> Implement limit pushdown through outer join in CBO
> --------------------------------------------------
>
> Key: HIVE-11684
> URL: https://issues.apache.org/jira/browse/HIVE-11684
> Project: Hive
> Issue Type: New Feature
> Components: CBO
> Affects Versions: 2.0.0
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Attachments: HIVE-11684.01.patch, HIVE-11684.02.patch,
> HIVE-11684.03.patch, HIVE-11684.04.patch, HIVE-11684.05.patch,
> HIVE-11684.patch
>
>
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