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From "Ashutosh Chauhan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-7159) For inner joins push a 'is not null predicate' to the join sources for every non nullSafe join condition
Date Thu, 19 Jun 2014 15:54:24 GMT

    [ https://issues.apache.org/jira/browse/HIVE-7159?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14037450#comment-14037450
] 

Ashutosh Chauhan commented on HIVE-7159:
----------------------------------------

{code}
if (prunedCols.size() != inputRR.getRowSchema().getSignature().size()
{code}

Is it better to do tighter check to make sure indeed all columns are identical before and
after, else it may be the case that there are 5 columns in prunedCols and in RowSchema, but
those are 5 different columns in two lists.

> 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, HIVE-7159.7.patch, HIVE-7159.8.patch, HIVE-7159.9.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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