Re: Out of date comment in cached_plan_cost

On 9 December 2017 at 06:05, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Thu, Dec 7, 2017 at 3:14 AM, David Rowley
> <david(dot)rowley(at)2ndquadrant(dot)com> wrote:
>> The attached is my attempt at putting this right.
>
> I don't feel entirely right about the way this seems to treat
> inheritance and partitioning as two entirely separate features; that's
> true from a user perspective, more or less, but not internally to the
> code.

Originally I had it typed out in a way that mentioned something about
"unless using partition-wise join with partitioned tables", but I felt
that the partition planning code is in such a state of flux at the
moment that I feared that comment might get outdated again someday in
the near future.

I've attached another patch which just loosens the claim that join
planning situation is never made worse by inheritance children to now
say it does not "generally" make any worse.

> Of course, this also begs the question of whether we ought to be
> changing the formula somehow.

Perhaps, but not for this patch. The comment already mentions that the
code is far from perfect.

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