On 30/10/2023 09:24, Richard Guo wrote:
>
> On Sun, Oct 29, 2023 at 11:56 PM Tom Lane <tgl@sss.pgh.pa.us
> <mailto:tgl@sss.pgh.pa.us>> wrote:
>
> Alexander Korotkov <aekorotkov@gmail.com
> <mailto:aekorotkov@gmail.com>> writes:
> > I made some beautification of the patch by Andrei. I also
> removed the
> > part which changes the target list for estimate_num_groups(). Any
> > objections to pushing this?
>
> It seems moderately likely that this will break as much as it fixes.
>
> I've not studied the original patch enough to understand why you need
> to be playing strange games with tree mutation rules, but I suspect
> that this is band-aiding over some rather fundamentally bad code.
>
>
> I also have some concerns about this patch. It requires that
> root->parse remains unchanged during the whole subquery_planner() in
> order to work, which is an implicit constraint we did not have before.
It is not about unchanged; it is about referencing the same query at the
parent and child query blocks. Am I missing something?
--
regards,
Andrei Lepikhov
Postgres Professional