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https://issues.apache.org/jira/browse/HIVE-12017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14997589#comment-14997589
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Ashutosh Chauhan commented on HIVE-12017:
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Code changes look good. Whats the reason for writing and using
HiveRelOptUtil::createProject() instead of calcite's RelOptUtil version? It
will be good to add reason as a comment in the code.
Also, as a side note, we will also want to add a profile, which will run all
rules which don't need stats. e.g, even if there are 3 joins but no stats, we
will not apply transitive inference rules for ppd for joins, because currently
CBO will throw exception when stats are not found. We should add such a profile
in a followup.
I am going through plan changes (slowly, slowly : ))
> Do not disable CBO by default when number of joins in a query is equal or
> less than 1
> -------------------------------------------------------------------------------------
>
> Key: HIVE-12017
> URL: https://issues.apache.org/jira/browse/HIVE-12017
> Project: Hive
> Issue Type: Improvement
> Components: CBO
> Affects Versions: 2.0.0
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Attachments: HIVE-12017.01.patch, HIVE-12017.02.patch,
> HIVE-12017.03.patch, HIVE-12017.04.patch, HIVE-12017.05.patch,
> HIVE-12017.06.patch, HIVE-12017.07.patch, HIVE-12017.08.patch
>
>
> Instead, we could disable some parts of CBO that are not relevant if the
> query contains 1 or 0 joins. Implementation should be able to define easily
> other query patterns for which we might disable some parts of CBO (in case we
> want to do it in the future).
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