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https://issues.apache.org/jira/browse/HIVE-12017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15011296#comment-15011296
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Ashutosh Chauhan commented on HIVE-12017:
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JOIN-GBY transpose rule is now cost based, so you may want to exclude it from
catch block.
For now putting non-cost-needing rules in catch block is fine, but I think we
need effort similar to HIVE-11110 for this set of rules to simplify this
try-catch based approach in future.
> 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,
> HIVE-12017.09.patch, HIVE-12017.10.patch, HIVE-12017.11.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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