Re: Postresql 8.0 Beta 3 - SELECT ... FOR UPDATE - Mailing list pgsql-hackers

From Rod Taylor
Subject Re: Postresql 8.0 Beta 3 - SELECT ... FOR UPDATE
Date
Msg-id 1101355158.44437.133.camel@home
Whole thread Raw
In response to Re: Postresql 8.0 Beta 3 - SELECT ... FOR UPDATE  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-hackers
On Wed, 2004-11-24 at 22:47 -0500, Bruce Momjian wrote:
> Rod Taylor wrote:
> > On Wed, 2004-11-24 at 22:13 -0500, Bruce Momjian wrote:
> > > 
> > > We have discussed this at length and no one could state why having an
> > > timeout per lock is any better than using a statement_timeout.
> > 
> > Actually, I hit one.
> > 
> > I have a simple queue and a number of processes pulling jobs out of the
> > queue. Due to transactional requirements, the database is appropriate
> > for a first cut.
> > 
> > Anyway, a statement_timeout of 100ms is usually plenty to determine that
> > the job is being processed, and for one of the pollers to move on, but
> > every once in a while a large job (4 to 5MB chunk of data) would find
> > itself in the queue which takes more than 100ms to pull out.
> > 
> > Not a big deal, just bump the timeout in this case.
> > 
> > Anyway, it shows a situation where it would be nice to differentiate
> > between statement_timeout and lock_timeout OR it demonstrates that I
> > should be using userlocks...
> 
> Wouldn't a LOCK NOWAIT be a better solution?  That is new in 8.0.

On a for update?

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