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

On 20 April 2018 at 14:07, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> To clarify: if we're going to add a new parameter *for partitioned tables*
> to configure whether or not pruning occurs, even if UPDATE and DELETE now
> rely on constraint exclusion for pruning, we should ignore the setting of
> constraint_exclusion the configuration parameter. For UPDATE and DELETE,
> if enable_partition_pruning is on, we proceed to prune using constraint
> exclusion (because that's the only method available now), irrespective of
> the setting of constraint_exclusion.
>
> So to users, enable_partition_pruning should be the only way to configure
> whether or not pruning occurs.

I hope the attached implements what is being discussed here.

Please test it to ensure it behaves as you'd expect.

I was a little unsure if the new GUCs declaration should live in
costsize.c or not since it really has no effect on plan costs, but in
the end, I stuck it there anyway so that it can be with its friends.

--
David Rowley http://www.2ndQuadrant.com/
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