AFAIK, file locks are new to JDK 1.4 and the behivor can vary slightly on
different platforms.
As I understand it, select for update is used to get an exclusive lock on
the data selected for the term of the transaction. This behivor is not
always desireable. There are certain application that don't want any
transaction isolation. Some want for example a last commited transaction
updates the data. This can give you huge performance boost, at the risk of
data corruption, which doesn't matter in some cases.
Dain
----- Original Message -----
From: "Bill Burke" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, July 24, 2001 9:33 AM
Subject: RE: [JBoss-dev] ditch entity locking in favor of
<select-for-update>
> Why not just put a lock on the file? Same thing. I was thinking of
> <select-for-update> more in the abstract. The CMP mechanism or the
database
> type-mapping could define what <select-for-update> actually meant.
>
> Bill
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED]]On Behalf Of
> > Rickard Öberg
> > Sent: Tuesday, July 24, 2001 12:45 AM
> > To: [EMAIL PROTECTED]
> > Subject: Re: [JBoss-dev] ditch entity locking in favor of
> > <select-for-update>
> >
> >
> > >The recents questions posted by James Cook got me thinking. Maybe we
> > should
> > >ditch the current entity locking scheme in favor of using
> > ><select-for-update>. It would greatly simplify the entity/cache
locking
> > >mechanism, thus probably making it much more robust than it currently
is.
> > >Of course, we'd have to improve select-for-update so that it
> > worked across
> > a
> > >greater range of databases and keep the old entity/cache locking for
> > >databases that didn't. Also, what about BMP? Does the spec
> > allow for the
> > >container to pass on synchronization responsibities to the Bean
> > Developer?
> > >I'll have to check.
> >
> >
> > Note that not all Entities are backed by DBMS's. In the app I'm working
on
> > currently they almost never are. Instead, I'm using XML files as
> > the backing
> > store, so using select-for-update is not an option.
> >
> > /Rickard
> >
> >
> >
> >
> > _______________________________________________
> > Jboss-development mailing list
> > [EMAIL PROTECTED]
> > http://lists.sourceforge.net/lists/listinfo/jboss-development
> >
>
>
>
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