persistence@glassfish.java.net

[Fwd: [Issue 2465] New - Performance issue with left join JPQL query in Toplink Essentials]

From: Michael Bouschen <Michael.Bouschen_at_Sun.COM>
Date: Thu, 22 Feb 2007 17:01:53 +0100

Hi Peter,

recently there was a forum posting " Performance problem with left join
JPQL query in Toplink Essentials":
http://forums.java.net/jive/thread.jspa?threadID=23258&tstart=30
Is the issue you filed related to this? If yes, it might make sense to
add a note to the forum that the problem is tracked by issue 2465. What
do you think?

Regards Michael

attached mail follows:



https://glassfish.dev.java.net/issues/show_bug.cgi?id=2465
                 Issue #|2465
                 Summary|Performance issue with left join JPQL query in Toplink
                        | Essentials
               Component|glassfish
                 Version|9.1pe
                Platform|All
              OS/Version|All
                     URL|
                  Status|NEW
       Status whiteboard|
                Keywords|
              Resolution|
              Issue type|DEFECT
                Priority|P4
            Subcomponent|entity-persistence
             Assigned to|tware
             Reported by|pkrogh






------- Additional comments from pkrogh_at_dev.java.net Wed Feb 21 20:13:52 +0000 2007 -------
I have a JPQL query that looks like this:

Iterator<Foo> foos = em.createQuery("SELECT DISTINCT f FROM Foo f JOIN FETCH
f.bars").getResultList().iterator();

Each foo contains 2 bars.

Running this query with 1000 foos (and 2000 bars) in the database takes about 9
seconds. With 5000 takes about 150 seconds.

Note - if these instances are in the cache first, then the times are
drastically reduced (.5 seconds for 1000 foos).

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