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List:       ojb-user
Subject:    Re: DB dead lock issue with deletePersistent calls
From:       "Bruno CROS" <bruno.cros () gmail ! com>
Date:       2006-12-15 9:02:42
Message-ID: 36412d0c0612150102l2aee2f0fy6e63facedc6f9d7d () mail ! gmail ! com
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JIRA is post.

On 12/15/06, Armin Waibel <arminw@apache.org> wrote:
>
> Hi Bruno,
>
> Bruno CROS wrote:
> > Hi,
> >
> > Yessss, we get rid of those dead locks.
>
> Congratulation!
>
> >
> > Actually, OJB does not cause anything to have Oracle dead locks!!
>
> Phew!
>
> > Many
> > applications can have dead locks without any lines of bad (OJB) code.
> >
> > Bad locks are generated when oracle can 't do simple operations as
> > UPDATE OR
> > DELETE, when time to verify foreign key is simply too long ( > 1s) .
> This
> > can occur when a table reaches a big size (million of records) and if
> those
> > table haven't appropriate index on foreign key code. Mounting index on
> > foreign key code is necessary !! (Oracle 10)
> >
> > I suggest a doclet/option to generate automatically indexes based on
> > reverse
> > foreignkey  declaration code.
>
> Please open a feature request in OJB-JIRA
> http://issues.apache.org/jira/browse/OJB
>
> >
> > Anyway, a big information on documentation, about this need from big
> Oracle
> > databse.
> >
> > After, DB works very faster and do not throw dead locks errors
> ORA-00060. I
> > known, this trouble only concerns only Oracle usages. But i think it
> > have to
> > figure in documentation.
>
> I could add a new section in "Platform setting" doc with notes/tips for
> specific databases.
> http://db.apache.org/ojb/docu/guides/platforms.html
>
> If you send me the title and the text I will integrate it in OJB docs.
>
> regards,
> Armin
>
> >
> > Regards.
> >
> > Thanks for help.
> >
> >
> >
> > On 12/8/06, Armin Waibel <arminw@apache.org> wrote:
> >>
> >> Bruno CROS wrote:
> >> > No. I don't known how to write such a test. But i have an idea where
> it
> >> > occurs in the persistent graph.
> >> >
> >> > I use locks on OJB master object (at start of transaction) when
> >> possible
> >> > (even with delete). I think with this, two transactions can't run at
> >> the
> >> > same time on the same part of persistent graph.
> >>
> >> Only if implicit locking is enabled, else only the specified object is
> >> locked and not the whole graph. If not enabled you have to lock all
> >> objects before changing or deleting by yourself.
> >> You can enable implicit locking on a per tx manner using OJB's
> >> odmg-extensions - TxExt.
> >>
> >>
> http://db.apache.org/ojb/docu/guides/odmg-guide.html#The+TransactionExt+Interface
> >>
> >> In this case all referenced objects will implicit locked with the same
> >> lock mode as the master object (on very large object graphs this could
> >> slow down performance).
> >>
> >> regards,
> >> Armin
> >>
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> >>
> >>
> >
>
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