[jira] [Commented] (HIVE-15758) Allow correlated scalar subqueries with aggregates which has non-equi join predicates

["Pengcheng Xiong (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-15758?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16033999#comment-16033999 ] 

Pengcheng Xiong commented on HIVE-15758:
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[~vgarg] and [~ashutoshc], could u talk a little bit more about this? I could not understand why "when there is zero row, we can not rewrite the query. " In the example that you gave, it will always return one row for the inner query, right?

> Allow correlated scalar subqueries with aggregates which has non-equi join predicates
> -------------------------------------------------------------------------------------
>
>                 Key: HIVE-15758
>                 URL: https://issues.apache.org/jira/browse/HIVE-15758
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Logical Optimizer
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>              Labels: sub-query
>
> Queries such as 
> {code} select * from part where p_size <> (select count(p_size) from part pp where part.p_type <> pp.p_type); {code} are currently not allowed since HIVE doesn't know how to rewrite such queries to preserve the correctness for cases when there is zero row



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