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From "Mark Struberg (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (OPENJPA-2179) 'distinct' and 'join' combinations lead lots of unneccessary sub-queries for @Embedded and @Lob fields
Date Tue, 01 May 2012 21:03:04 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-2179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13266097#comment-13266097
] 

Mark Struberg commented on OPENJPA-2179:
----------------------------------------

weird, I did the tests on an Oracle 10 XE windows installation in a VM (the easiest way to
do oracle tests on a mac).

Actually you can remove the courseId field at all. It does not have any impact on the superfluous
sub-queries. txs!
                
> 'distinct' and 'join' combinations lead lots of unneccessary sub-queries for @Embedded
and @Lob fields
> ------------------------------------------------------------------------------------------------------
>
>                 Key: OPENJPA-2179
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-2179
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: kernel
>    Affects Versions: 2.2.0
>            Reporter: Mark Struberg
>            Assignee: Mark Struberg
>             Fix For: 2.3.0
>
>         Attachments: OPENJPA-2179-test-1.patch
>
>
> I have an Entity (Course) with a simple @Embedded field and a @Lob. I do not use any
LAZY attribution on them!
> If I do a normal em.find, the entity will be loaded as a whole (all the fields, including
the embedded and the lob will be fetched immediately).
> Sidenote: the Lecturer referred in the select is defined as
>     @OneToMany(mappedBy = "course",
>             cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.MERGE},
>             orphanRemoval = true, fetch = FetchType.EAGER)
>     @OrderColumn(name = "POSITION")
>     private List<Lecturer> lecturers;
> The following selects DO work
> * "select c from Course c join c.lecturers l "
> * "select distinct c from Course c"
> The following selects create tons of subqueries! 1 separate sub-query for each @Embedded
field, and also for each @Lob
> * "select distinct c from Course c join c.lecturers l "
> * "select distinct c from Lecturer l join l.course c"
> * "select c from Lecturer l join l.course c" 
> This happens ONLY if I run this stuff against Oracle. In MySQL it seems to work properly.
> I'll try to create a unit test for it.

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