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From "Brock Noland (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-8518) Compile time skew join optimization returns duplicated results
Date Wed, 22 Oct 2014 02:18:34 GMT

    [ https://issues.apache.org/jira/browse/HIVE-8518?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14179484#comment-14179484
] 

Brock Noland commented on HIVE-8518:
------------------------------------

There is some results difference s that I cannot account for. Since I am off the rest of the
week I think we should merge any individual fixes we want using {{svn merge -c$num ^/hive/trunk}}

I will finish the rest of the merge this weekend.

> Compile time skew join optimization returns duplicated results
> --------------------------------------------------------------
>
>                 Key: HIVE-8518
>                 URL: https://issues.apache.org/jira/browse/HIVE-8518
>             Project: Hive
>          Issue Type: Bug
>          Components: Logical Optimizer
>    Affects Versions: 0.14.0
>            Reporter: Rui Li
>            Assignee: Rui Li
>             Fix For: 0.15.0
>
>         Attachments: HIVE-8518.1.patch
>
>
> Compile time skew join optimization clones the join operator tree and unions the results.
> The problem here is that we don't properly insert the predicate for the cloned join (relying
on an assert statement).
> To reproduce the issue, run the simple query:
> {code}select * from tbl1 join tbl2 on tbl1.key=tbl2.key;{code}
> And suppose there's some skew in tbl1 (specify skew with CREATE or ALTER statement).
> Duplicated results will be returned if you set hive.optimize.skewjoin.compiletime=true.



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