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https://issues.apache.org/jira/browse/HIVE-7724?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14096571#comment-14096571
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Harish Butani commented on HIVE-7724:
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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|https://issues.apache.org/jira/browse/HIVE-5830]
> CBO: support Subquery predicates
> --------------------------------
>
> Key: HIVE-7724
> URL: https://issues.apache.org/jira/browse/HIVE-7724
> Project: Hive
> Issue Type: Sub-task
> Reporter: Harish Butani
> Assignee: Harish Butani
> Attachments: HIVE-7724.rewriteInHive.prelim.patch
>
>
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