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https://issues.apache.org/jira/browse/HIVE-13076?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15280794#comment-15280794
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Ruslan Dautkhanov commented on HIVE-13076:
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That's awesome. Thanks a lot [~hsubramaniyan]
> Implement FK/PK "rely novalidate" constraints for better CBO
> ------------------------------------------------------------
>
> Key: HIVE-13076
> URL: https://issues.apache.org/jira/browse/HIVE-13076
> Project: Hive
> Issue Type: Improvement
> Components: CBO, Logical Optimizer
> Reporter: Ruslan Dautkhanov
> Assignee: Hari Sankar Sivarama Subramaniyan
> Fix For: 2.1.0
>
>
> Oracle has "RELY NOVALIDATE" option for constraints.. Could be easier for
> Hive to start with something like that for PK/FK constraints. So CBO has more
> information for optimizations. It does not have to actually check if that
> constraint is relationship is true; it can just "rely" on that constraint..
> https://docs.oracle.com/database/121/SQLRF/clauses002.htm#sthref2289
> So it would be helpful with join cardinality estimates, and with cases like
> this - https://issues.apache.org/jira/browse/HIVE-13019
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