Re: Row Lock

On Fri, 2003-10-03 at 15:34, Dave Tenny wrote:
> -- begin transaction
> SELECT rowstuff FROM table WHERE record-of-interest = somekey FOR
> UPDATE
> ... get new value from the user
> UPDATE rowstuff WHERE record-of-interest = somekey
> COMMIT
>
> -----------------------
>
> However, it is considered exceedly poor application design to have any
> interactive
> dialogs in the midst of a transaction.  (Really bad, don't do it!
> You'll block potentially all users
> for potentially unlimited amounts of time).
>
> Suggest you get the row value, remember it, present to the user for
> update OUTSIDE a transaction,
> then start a transaction to update when you have the new value.  If
> the row value has changed to something incompatible
> with the user's value, abort and complain, otherwise do the update.

Hello,
I also have to do a similar program and I ended up implementing this
exact scheme.
But I had to use hashes of the record to check if it was changed because
it seems like the proper function, expressely designed for that is not
implementend: ResultSet.rowUpdated().

Do you know if there are plans of supporting it?

It would be a great boost for JDBC applications.

Thanks,
Alex


> Waldomiro wrote:
> > Hello,
> >
> > I have an aplication which ask a code to bring up the data on
> > screen, then the user can change the data and save it.
> >
> > My problem is :
> >
> > 2 users at same time can put the same code and make diferent
> > changes.
> >
> > Are there any way to lock this record in postgres when the first
> > user is changing the data on screen ?
> >
> > What shoud I do ?
> >
> > Thanks
> >
> > Waldomiro C Neto.
> > Shx Informática Ltda.
> > +55 (11) 5581-1551
> > www.shx.com.br
> > wmiro@shx.com.br
> >