[jira] [Updated] (HIVE-7159) For inner joins push a 'is not null predicate' to the join sources for every non nullSafe join condition

["Harish Butani (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-7159?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Harish Butani updated HIVE-7159:
--------------------------------

    Attachment: HIVE-7159.1.patch

preliminary patch attached.

> 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
>         Attachments: HIVE-7159.1.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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