Re: generic plans and "initial" pruning

Hi Thom,

On Tue, Jul 18, 2023 at 1:33 AM Thom Brown <thom(at)linux(dot)com> wrote:
> On Thu, 13 Jul 2023 at 13:59, Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> > In an absolutely brown-paper-bag moment, I realized that I had not
> > updated src/backend/executor/README to reflect the changes to the
> > executor's control flow that this patch makes. That is, after
> > scrapping the old design back in January whose details *were*
> > reflected in the patches before that redesign.
> >
> > Anyway, the attached fixes that.
> >
> > Tom, do you think you have bandwidth in the near future to give this
> > another look? I think I've addressed the comments that you had given
> > back in April, though as mentioned in the previous message, there may
> > still be some funny-looking aspects still remaining. In any case, I
> > have no intention of pressing ahead with the patch without another
> > committer having had a chance to sign off on it.
>
> I've only just started taking a look at this, and my first test drive
> yields very impressive results:
>
> 8192 partitions (3 runs, 10000 rows)
> Head 391.294989 382.622481 379.252236
> Patched 13088.145995 13406.135531 13431.828051

Just to be sure, did you use pgbench --Mprepared with plan_cache_mode
= force_generic_plan in postgresql.conf?

> Looking at your changes to README, I would like to suggest rewording
> the following:
>
> +table during planning. This means that inheritance child tables, which are
> +added to the query's range table during planning, if they are present in a
> +cached plan tree would not have been locked.
>
> To:
>
> This means that inheritance child tables present in a cached plan
> tree, which are added to the query's range table during planning,
> would not have been locked.
>
> Also, further down:
>
> s/intiatialize/initialize/
>
> I'll carry on taking a closer look and see if I can break it.

Thanks for looking. I've fixed these issues in the attached updated
patch. I've also changed the position of a newly added paragraph in
src/backend/executor/README so that it doesn't break the flow of the
existing text.

--
Thanks, Amit Langote
EDB: http://www.enterprisedb.com