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From "Ruslan Dautkhanov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-13076) Implement FK/PK "rely novalidate" constraints for better CBO
Date Wed, 11 May 2016 20:44:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-13076?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15280794#comment-15280794
] 

Ruslan Dautkhanov commented on HIVE-13076:
------------------------------------------

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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