Hi, If you feel FOR UPDATE is taking much time, then I believe,we can solve this kind of issues using advisory locks <http://www.postgresql.org/docs/9.1/static/explicit-locking.html>, .
Regards, Dinesh manojadinesh.blogspot.com On Wed, Feb 18, 2015 at 10:45 AM, Bill Moran <wmo...@potentialtech.com> wrote: > On Wed, 18 Feb 2015 18:30:09 +0000 > Dmitry O Litvintsev <litvi...@fnal.gov> wrote: > > > > Yes, deadlock occurs when there are multiple processes insert > > concurrently into file table with the same volume id field. > > I used "sometimes" as opposed to "all the time". > > I resonded in that way since I frequently hear people complaining, > "we're seeing all kinds of deadlocks" as if the whole world is > collapsing under the deadlocks, but when pressed for more information > it turns out they're only seeing a few deadlocks per hour when the > system is under the heaviest load -- that scenario is hardly > unexpected. As a result, having more detailed information than > just "sometimes" helps to understand what's really going on. > > > I think you advise to retry transaction or add select for update prior > > to insert. I will pursue this (together with upgrade to 9.3.6 suggested > by > > Alvaro). > > The nice thing about a retry strategy is that it always works. > The problem with a retry strategy is that it's easy to do wrong > (i.e. it may be more than just the transaction that needs to > restart ... depending on what data has changed, calculations may > need to be redone, the user requeried for certain information, > etc). > > The problem with the SELECT ... FOR UPDATE is that it's a bit > slower, and can be significantly slower unders some circumstances, > but it's easier to implement correctly. > > The good news form Alvaro is that this is probably happening more > frequently than necessary because of the bug he mentioned ... so > upgrading may cause the problem to happen infrequently enough that > you don't really care about it. The solutions I suggest are still > relevent, they just might not be as immediately important. > > -- > Bill Moran > > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general >
