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From "Harish Butani (JIRA)" <>
Subject [jira] [Commented] (HIVE-7724) CBO: support Subquery predicates
Date Thu, 14 Aug 2014 04:56:17 GMT


Harish Butani commented on HIVE-7724:

There are 2 options for this:
* *Rewrite in Hive:* use the existing rewrite rules from Hive to convert _SubQuery_ predicates
to equivalent Relational expressions. 
*# requires /SemiJoins/ to be supported. For e.g. with this path, the SemiJoin conversion
for _in predicates_ throws an error in *ConvertMultiJoinRule*
*# We miss out on Optiq's broader support of Subquery predicates ( multiple Subquery predicates
in a QueryBlock, nested Subquery predicates etc.)
*# preliminary patch is attached that works for Not-In (and probably not exists). Several
tests for Not-In. Not-In/Not exists don't need SemiJoin.

* *Use Optiq's Correlation RelNode:* 
*# Currently Optiq has infrastructure to construct a *Correlation RelNode*, and conversion
to equivalent Relational expressions based on state maintained in _SqlNodeConverter_. This
will have to be factored out of SqlNodeConverter.
*# Need to investigate Optiq's rules to see if we need to add additional stuff. For e.g. [the
Not In Null Check that Hive handles|]

> CBO: support Subquery predicates
> --------------------------------
>                 Key: HIVE-7724
>                 URL:
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Harish Butani
>            Assignee: Harish Butani
>         Attachments: HIVE-7724.rewriteInHive.prelim.patch

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