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From "Harish Butani (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-7159) For inner joins push a 'is not null predicate' to the join sources for every non nullSafe join condition
Date Sat, 31 May 2014 17:41:01 GMT
Harish Butani created HIVE-7159:
-----------------------------------

             Summary: 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


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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