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From "Matt Tucker (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5555) Support alternate join syntax: joining conditions in where clause; also pushdown qualifying join conditions
Date Thu, 12 Dec 2013 23:17:07 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13846888#comment-13846888
] 

Matt Tucker commented on HIVE-5555:
-----------------------------------

It's a nice to have.  Just wanted to make sure that syntax was covered since it's similar
to the other examples.

> 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
>          Components: Query Processor
>            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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