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From "Harish Butani (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-5555) Support alternate join syntax: joining conditions in where clause; also pushdown qualifying join conditions
Date Wed, 16 Oct 2013 00:51:41 GMT
Harish Butani created HIVE-5555:
-----------------------------------

             Summary: Support alternate join syntax: joining conditions in where clause; also
pushdown qualifying join conditions 
                 Key: HIVE-5555
                 URL: https://issues.apache.org/jira/browse/HIVE-5555
             Project: Hive
          Issue Type: Bug
            Reporter: Harish Butani
            Assignee: Harish Butani
         Attachments: AlternativeJoinSyntax.pdf

Certain tools still generate `old style' Join queries where the join
condition is in the Where clause. A related set of issues that can
be addressed is that of pushing forward joining conditions;
in a manner similar to the Predicate Pushdown feature of Hive.

For e.g. these queries can have join conditions pushed down:

{noformat}
- query 1, push join predicate from 2nd join to 1st
explain select *
from part p1 join part p2 join part p3 on p1.p_name = p2.p_name and p2.p_name = p3.p_name;

- query 2
explain select *
from part p1 join part p2 join part p3 
where p1.p_name = p2.p_name and p2.p_name = p3.p_name;
{noformat}



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