Re: Change lock requirements for adding a trigger

On Wed, 2008-06-04 at 16:33 -0400, Tom Lane wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
> > We have
> > * relhasindex (bool) set by CREATE INDEX but not unset by DROP INDEX
> > * relhasrules (bool)
> > * reltriggers (int2)  set by CREATE and DROP, since its an integer
> 
> Right.
> 
> > If CREATE INDEX can take a Share lock and can update pg_class, why would
> > it not be theoretically possible for CREATE TRIGGER? 
> 
> It's (probably) theoretically possible, if we replace reltriggers with a
> bool that acts more like relhasindex, ie it's a hint to go look in
> pg_triggers.  My point was just that you can't arbitrarily decide that
> some operation needs only a given strength of lock if you are not up to
> speed on these sorts of details.

Understood. Wouldn't have looked there without your hint.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support