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Date: Mon, 16 Jun 2014 10:09:02 +0000 (UTC)
From: "Gunther Hagleitner (JIRA)" <jira@apache.org>
To: hive-dev@hadoop.apache.org
Message-ID: <JIRA.12717740.1401557979069.136548.1402913342628@arcas>
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Subject: [jira] [Updated] (HIVE-7159) For inner joins push a 'is not null
 predicate' to the join sources for every non nullSafe join condition
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     [ https://issues.apache.org/jira/browse/HIVE-7159?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gunther Hagleitner updated HIVE-7159:
-------------------------------------

    Attachment: HIVE-7159.6.patch

More golden file updates in 6.

There seems to be a couple of issues though that are either wrong with this patch or might be exposing problems with the original code:

a) subquery transformation doesn't generate the nullsafe array (already addressed in patch)
b) join pushdown does not seem to correctly populate the nullsafe array (size(join condns) != size(nullsafe))
c) Somehow this patch seems to change ptf/windowing tests results (actual query results, not just explain)

[~rhbutani] any thoughts?

> For inner joins push a 'is not null predicate' to the join sources for every non nullSafe join condition
> --------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-7159
>                 URL: https://issues.apache.org/jira/browse/HIVE-7159
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Harish Butani
>            Assignee: Harish Butani
>         Attachments: HIVE-7159.1.patch, HIVE-7159.2.patch, HIVE-7159.3.patch, HIVE-7159.4.patch, HIVE-7159.5.patch, HIVE-7159.6.patch
>
>
> A join B on A.x = B.y
> can be transformed to
> (A where x is not null) join (B where y is not null) on A.x = B.y
> Apart from avoiding shuffling null keyed rows it also avoids issues with reduce-side skew when there are a lot of null values in the data.
> Thanks to [~gopalv] for the analysis and coming up with the solution.


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