On Sun, Aug 3, 2008 at 1:40 AM, Berend Tober <btober@xxxxxxxxxxxxxxxx> wrote: > > > The way I understand the documentation at > > "http://www.postgresql.org/docs/8.3/static/transaction-iso.html"; > > and > > 'http://www.postgresql.org/docs/current/static/explicit-locking.html', > > you should not have to use the serial isolation level. > > I would define the counter table so as to hold the last-used value, rather > that the "next" value, and then do the UPDATE first. > > As a consequence, assuming all this happens within a transaction of course, > the SELECT FOR UPDATE syntax is not required either because the UPDATE will > grab a lock on the row and block other updates until the transaction is > finished. That is, concurrency is protected and you don't have to restart > any transactions because subsequent transactions will just wait until the > first one finishes due to nature of the lock automatically acquired by the > initial UPDATE statement. > Yes, I'm considering moving away from serializable; the problem is that I have to explore all the implications of this on my code. Up to now, I wrote considering a serializable level, so I think I should do quite a review to be sure about it. Regards Marco -- Marco Bizzarri http://iliveinpisa.blogspot.com/
