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From "Harish Butani (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-6643) Add a check for cross products in plans and output a warning
Date Wed, 12 Mar 2014 23:51:42 GMT
Harish Butani created HIVE-6643:
-----------------------------------

             Summary: Add a check for cross products in plans and output a warning
                 Key: HIVE-6643
                 URL: https://issues.apache.org/jira/browse/HIVE-6643
             Project: Hive
          Issue Type: Bug
            Reporter: Harish Butani
            Assignee: Harish Butani
         Attachments: HIVE-6643.1.patch

Now that we support old style join syntax, it is easy to write queries that generate a plan
with a cross product.
For e.g. say you have A join B join C join D on A.x = B.x and A.y = D.y and C.z = D.z
So the JoinTree is:

A — B
|__  D — C

Since we don't reorder join graphs, we will end up with a cross product between (A join B)
and C



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