Re: problems with table corruption continued

On Wed, 19 Dec 2001, Hiroshi Inoue wrote:

> Stephan Szabo wrote:
> >
> > On Tue, 18 Dec 2001, Tom Lane wrote:
> >
> > > The ri_triggers code has a lot of places that open things NoLock,
> > > but it only looks into the relcache entry and doesn't try to scan
> > > the relation. Nonetheless that code bothers me; we could be using
> > > an obsolete relcache entry if someone has just committed an ALTER
> > > TABLE on the relation. Some of the cases may be safe because a lock
> > > is held higher up (eg, on the table from which the trigger was fired)
> > > but I doubt they all are.
> >
> > Probably not, since it looks like that's being done for the other table of
> > the constraint (not the one on which the trigger was fired).
>
> If a lock is held already, acquiring an AccessShareLock
> would cause no addtional conflict. I don't see any reason
> to walk a tightrope with NoLock intentionally.

I don't know why NoLock was used there, I was just pointing out that the
odds of a lock being held higher up is probably low.