Should we add GUCs to allow partition pruning to be disabled?

On Wednesday, May 2, 2018, Alvaro Herrera <alvherre@2ndquadrant.com> wrote:

Robert Haas wrote:
> On Wed, May 2, 2018 at 9:28 AM, Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
> > I admit I am more concerned about the possibility of bugs than I am
> > about providing a performance-related tool.
>
> I agree that if partition pruning has bugs, somebody might want to
> turn it off.  On the other hand, when they do, there's a good chance
> that they will lose so much performance that they'll still be pretty
> sad.  Somebody certainly could have a workload where the pruning
> helps, but by a small enough amount that shutting it off is
> acceptable.  But I suspect that's a somewhat narrow target.
>
> I'm not going to go to war over this, though.  I'm just telling you
> what I think.

Well, we didn't have a GUC initially, evidently because none of us
thought that this would be a huge problem.  So maybe you're both right
and it's overkill to have it.  I'm not set on having it, either.  Does
anybody else have an opinion?