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From "Xuefu Zhang (JIRA)" <>
Subject [jira] [Commented] (HIVE-8518) Compile time skew join optimization returns duplicated results
Date Wed, 22 Oct 2014 02:12:34 GMT


Xuefu Zhang commented on HIVE-8518:

I think [~brocknoland] is in the middle of merging trunk to branch. This, in addition to a
few other important patches will be included, I assume.

> Compile time skew join optimization returns duplicated results
> --------------------------------------------------------------
>                 Key: HIVE-8518
>                 URL:
>             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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