Hi Sashutosh!
----- Original Message -----
From: "Ashutosh" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, January 31, 2001 7:07 AM
Subject: Re: Two instances of an EB over the same row
> Hello Carlos,
> To add to the original query :
> Taking the case of the highest isolation level
> (Serialisable) i presume that the table would be locked when one instance
> has selected a row but has not commited any changes. The other instance
> would not be able to even select the data from that row unless the first
> instance puts in the commited changes.
> Will this not affect the performance terribly (ofcourse,
at
> the advantage of maintaining data integrity)?
Yes this will be the case. I sounds as if you were expecting something new
from EJBs. EJBs just add easy development and declarative transaction
programming. They never have been expected to introduce a new model of
transaction management.
> When the second instance tries to read from the row, will
> the container make it wait till the row has been released OR throw an
> exception ??
I don´t think this is a container issue. Transaction Manager, if used, will
be the responsible for this behavior. I´m not sure what is the algorithm for
this situation. I woul expect a short number of retries behind the scene
(~ms) and an exception later.
> Thanks for your time.
Regards.
> Ashutosh.
>
>
> ----- Original Message -----
> From: "Carlos Otero Barros" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Tuesday, January 30, 2001 1:19 PM
>
>
> > Hi.
> > Not sure what you mean by "SELECT FOR UPDATE".
> > Two instances of the same Entity Bean over the same row still have
> different
> > transaction contexts.
> > You may expect isolation from transactions so you can rely on them.
> > If two users try to update the row almost at the same time from
different
> > instances of the same class of Entity Bean then the standard transaction
> > approach applies.
> >
> > Regards.
> >
> > ----- Original Message -----
> > From: "manishi tuli" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Tuesday, January 30, 2001 7:53 PM
> >
> >
> > > if 2 instances of ejb are trying to update same row , can we handle
this
> > > thing with ejb transaction or we have to do with select for update
> > >
> > > thanks
> > >
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