if user1 set Resultset rs to ResultSet.TYPE_SCROLL_SENSITIVE and using
refreshRow() in rs. The rs might show the updated record within this
rs updated by user2.
The pessimistic locking seems a good method. How can I do it by
programming or set up something in DBMS ? Could you please advise me?
I need to set up row lock to prevent 2 users update same record
concurrently. If I use synchronized method it may cause deadlock.
Thanks
pg@fastcrypt.com (Dave Cramer) wrote in message news:<1082479857.3069.178.camel@localhost.localdomain>...
> the driver isn't automagically going to update your records if someone
> changes them in the db while you have the result set loaded in your
> program.
>
> You need to do one of two things, either use pessimistic locking, ie
> select for update, and lock the row, or use optimistic locking and
> timestamp the updates so that when you commit your changes then you will
> see that the timestamp in your local record is different than the
> timestamp in the database and realize your data is stale.
>
> There is another way, but it is not ready yet, we are working on pl/j
> which is a java procedural language that would allow you to do the magic
> above. ie create a java procedure that you called on a trigger which
> would update your local copy of the data if someone else were to change
> it
>
> If you are interested and brave, have a look at plj.codehaus.org for the
> pl/j code, but beware this is alpha quality code.
>
> Dave
> On Thu, 2004-04-15 at 15:23, kenchen077 wrote:
> > Hi all,
> >
> > I am building web application by using Oracle data base.
> > Because different uders will manipulate the same data record at the
> > same time.
> > Could someone please help me for the following questions:
> >
> > 1. How can I handel the concurrently DML (insert, update, delete)
> > opertions on same data record by different users? Can I use
> > synchronied method in update, insert, and delete opertionns? Or other
> > better method ??
> >
> > 2. When user 1 select data from table , user 2 update or delete the
> > date in the same table concurrently.
> > Do I need to set transaction isolation level to
> > TRANSACTION_READ_COMMITED or refreshRow() to get the updated data?
> >
> > thanks all.
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 8: explain analyze is your friend
> >
> >
> >
> > !DSPAM:4085512d14457238818707!
> >
> >
> --
> Dave Cramer
> 519 939 0336
> ICQ # 14675561
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)