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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 Mon, 30 Apr 2012 08:13:45 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-2179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13264718#comment-13264718
] 

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

I've now committed a unit test which shows the problem. The new TestOracleDistinctJoin also
contains a guide howto invoke this test on the commandline.

The test will give the following output (amonst others), where you can clearly see that SomeEmbeddable
get's fetched via a separate SQL statement, even though there is no LAZY loading set on the
Embedded field:

1348  test  TRACE  [main] openjpa.Query - Executing query: select c from Lecturer l join l.course
c
1348  test  TRACE  [main] openjpa.jdbc.SQL - <t 270142182, conn 754307120> executing
prepstmnt 960389670 SELECT t1.ID, t1.OPTLOCK, t1.COURSENUMBER, t1.NORMALATTRIBUTE FROM SMSGW.Lecturer
t0, SMSGW.Course t1 WHERE t0.COURSE_ID = t1.ID
1350  test  TRACE  [main] openjpa.jdbc.SQL - <t 270142182, conn 754307120> [2 ms] spent
1350  test  TRACE  [main] openjpa.jdbc.SQLDiag - load: class org.apache.openjpa.jdbc.oracle.SomeEmbeddable
oid: 2551
1350  test  TRACE  [main] openjpa.jdbc.SQL - <t 270142182, conn 754307120> executing
prepstmnt 2034408626 SELECT t0.OBJECTIVEDE, t0.OBJECTIVEEN FROM SMSGW.Course t0 WHERE t0.ID
= ? [params=?]
1351  test  TRACE  [main] openjpa.jdbc.SQL - <t 270142182, conn 754307120> [1 ms] spent
1354  test  TRACE  [main] openjpa.jdbc.SQLDiag - load: class org.apache.openjpa.jdbc.oracle.Course
oid: 2551
1354  test  TRACE  [main] openjpa.jdbc.SQLDiag - Eager relations: [org.apache.openjpa.jdbc.oracle.Course.lecturers]
1354  test  TRACE  [main] openjpa.jdbc.SQL - <t 270142182, conn 754307120> executing
prepstmnt 698114403 SELECT t0.LOBCOLUMN, t1.COURSE_ID, t1.POSITION, t1.ID, t1.OPTLOCK, t1.NAME
FROM SMSGW.Course t0, SMSGW.Lecturer t1 WHERE t0.ID = ? AND t0.ID = t1.COURSE_ID(+) ORDER
BY t1.COURSE_ID ASC, t1.POSITION ASC [params=?]
1355  test  TRACE  [main] openjpa.jdbc.SQL - <t 270142182, conn 754307120> [1 ms] spent
                
> '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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