Re: DB dead lock issue with deletePersistent calls

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 <[email protected]> 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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>