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From "bernard (JIRA)" <j...@apache.org>
Subject [jira] Updated: (OPENJPA-1553) JPQL simple Child query generates unnecessary Table Join
Date Sun, 07 Mar 2010 20:20:27 GMT

     [ https://issues.apache.org/jira/browse/OPENJPA-1553?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

bernard updated OPENJPA-1553:
-----------------------------

    Attachment: SimpleJoin.zip

Testcase, NetBeans project in zip file

> JPQL simple Child query generates unnecessary Table Join
> --------------------------------------------------------
>
>                 Key: OPENJPA-1553
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-1553
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: jpa
>    Affects Versions: 2.0.0-beta2
>         Environment: Java 6
>            Reporter: bernard
>         Attachments: SimpleJoin.zip
>
>
> The attached testcase demonstrates that for a basic child query, OpenJPA generates SQL
that contains two joined tables where only one is required.
> SELECT t0.id, t1.id FROM Child t0 LEFT OUTER JOIN Parent t1 ON t0.PARENT_ID = t1.id WHERE
(t0.PARENT_ID = ?)
> This creates performance issues. Please note that this is a simplified testcase - performance
issues are of course not present in it.
> It can be expected that JPA that provides a layer of abstraction by nature, generates
optimized SQL.
> In light of the fact that this is a 2.0 release, the priority of solving this should
be high.

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