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

On Wed, May  2, 2018 at 07:49:42PM -0700, David G. Johnston wrote:
> 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?
> 
> 
> I toss my +1 to removing it altogether.

+1  We are terrible at removing old GUCs and having it around means
everyone has to decide if they need to change it, so having it is not a
zero cost.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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