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From "Matt McCline (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-18769) Vectorization: Disable vectorization of key-less outer joins
Date Thu, 22 Feb 2018 07:33:03 GMT

    [ https://issues.apache.org/jira/browse/HIVE-18769?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16372514#comment-16372514
] 

Matt McCline commented on HIVE-18769:
-------------------------------------

[~gopalv] thank you for figuring this problem out.

> Vectorization: Disable vectorization of key-less outer joins
> ------------------------------------------------------------
>
>                 Key: HIVE-18769
>                 URL: https://issues.apache.org/jira/browse/HIVE-18769
>             Project: Hive
>          Issue Type: Bug
>          Components: Vectorization
>    Affects Versions: 3.0.0
>            Reporter: Gopal V
>            Assignee: Gopal V
>            Priority: Major
>
> Left & Right outer joins without keys are valid in SQL and they have different semantics
from cross-products
> {code}
> create temporary table foo(x int) stored as orc;
> insert into foo values(1),(2);
> create temporary table bar(y int) stored as orc;
> select count(*) from bar right outer join foo; -- = 2
> select count(*) from bar, foo; -- = 0 
> {code}
> canSpecializeMapJoin should bail on these cases.



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