PB Tutorial (ERROR) and question

[Daniel Perry <d....@netcase.co.uk>]

I was just reading the tutorial on the PB API, and came accross a slight error:
In the "Deleting Persistent Objects",
PersistenceBrokerFactory.defaultPersistenceBroker();
Should be:
broker = PersistenceBrokerFactory.defaultPersistenceBroker();

One more thing, using ODMG i have been doing tx.markDirty(object) to update an object outside of a transaction. If i do a broker.store(object) outside of a transaction will this have the same effect?

Thanks,
Daniel.

Re: PB Tutorial (ERROR) and question

[Philippe Hacquin <ha...@wanadoo.fr>]

Hi Brian,

nice to hear that; this is the way I handle updates on my objects, and 
it goes pretty well. To make things clear, tell me if I'm wrong, 
re-query the object by identity is the only way to get a reference to 
the object directly from the cache to avoid querying the database 
(provided OJB is configured with a cache, of course).

This is something that was not obvious when I first studied the 
tutorials (well, I began back in March last year, before you had a 
chance to enhance them), and may be worth to mention, in my opinion.


Brian McCallister wrote:

[...]

> 
> On the ODMG markDirty / store thing... I don't know for sure, but there 
> is a potential for lost updates when using markDirty(...). The practice 
> I have had recommended, and use, is to just re-query it by identity in 
> the bounds of a transaction and make the changes, rather than modifying 
> a persistent object outside of a transaction and forcing changes back in.

[...]


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Re: PB Tutorial (ERROR) and question

[Daniel Perry <d....@netcase.co.uk>]

Thanks,
That makes sense. Though in my current application there is practically no
chance of objects being concurrently updated.  And if it did happen, it
wouldn;t really matter.
However in future projects, i can see i will need to use transactions.

Thanks,
Daniel.
----- Original Message ----- 
From: "Brian McCallister" <mc...@forthillcompany.com>
To: "OJB Users List" <oj...@db.apache.org>
Sent: Wednesday, January 07, 2004 2:28 PM
Subject: Re: PB Tutorial (ERROR) and question


> On the tutorial type -- thank you! I just fixed in OJB_1_0 and HEAD =)
>
> On the ODMG markDirty / store thing... I don't know for sure, but there
> is a potential for lost updates when using markDirty(...). The practice
> I have had recommended, and use, is to just re-query it by identity in
> the bounds of a transaction and make the changes, rather than modifying
> a persistent object outside of a transaction and forcing changes back
> in.
>
> -Brian
>
> On Jan 7, 2004, at 5:49 AM, Daniel Perry wrote:
>
> > I was just reading the tutorial on the PB API, and came accross a
> > slight error:
> > In the "Deleting Persistent Objects",
> > PersistenceBrokerFactory.defaultPersistenceBroker();
> > Should be:
> > broker = PersistenceBrokerFactory.defaultPersistenceBroker();
> >
> > One more thing, using ODMG i have been doing tx.markDirty(object) to
> > update an object outside of a transaction. If i do a
> > broker.store(object) outside of a transaction will this have the same
> > effect?
> >
> > Thanks,
> > Daniel.
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ojb-user-unsubscribe@db.apache.org
> For additional commands, e-mail: ojb-user-help@db.apache.org
>
>


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Re: PB Tutorial (ERROR) and question

[Brian McCallister <mc...@forthillcompany.com>]

On the tutorial type -- thank you! I just fixed in OJB_1_0 and HEAD =)

On the ODMG markDirty / store thing... I don't know for sure, but there 
is a potential for lost updates when using markDirty(...). The practice 
I have had recommended, and use, is to just re-query it by identity in 
the bounds of a transaction and make the changes, rather than modifying 
a persistent object outside of a transaction and forcing changes back 
in.

-Brian

On Jan 7, 2004, at 5:49 AM, Daniel Perry wrote:

> I was just reading the tutorial on the PB API, and came accross a 
> slight error:
> In the "Deleting Persistent Objects",
> PersistenceBrokerFactory.defaultPersistenceBroker();
> Should be:
> broker = PersistenceBrokerFactory.defaultPersistenceBroker();
>
> One more thing, using ODMG i have been doing tx.markDirty(object) to 
> update an object outside of a transaction. If i do a 
> broker.store(object) outside of a transaction will this have the same 
> effect?
>
> Thanks,
> Daniel.



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