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From "Mark Struberg (JIRA)" <j...@apache.org>
Subject [jira] [Created] (OPENJPA-2179) 'distinct' and 'join' combinations lead lots of unneccessary sub-queries for @Embedded and @Lob fields
Date Thu, 26 Apr 2012 17:02:18 GMT
Mark Struberg created OPENJPA-2179:
--------------------------------------

             Summary: '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


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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