Re: type cache cleanup improvements

Hi, Alexander!

On Tue, 22 Oct 2024 at 11:34, Alexander Korotkov <aekorotkov(at)gmail(dot)com>
wrote:

> On Mon, Oct 21, 2024 at 2:30 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com>
> wrote:
> >
> > On Mon, Oct 21, 2024 at 1:16 PM Dagfinn Ilmari Mannsåker
> > <ilmari(at)ilmari(dot)org> wrote:
> > > Alexander Korotkov <aekorotkov(at)gmail(dot)com> writes:
> > >
> > > > On Mon, Oct 21, 2024 at 8:40 AM Andrei Lepikhov <lepihov(at)gmail(dot)com>
> wrote:
> > > >>
> > > >> On 21/10/2024 06:32, Dagfinn Ilmari Mannsåker wrote:
> > > >> > Alexander Korotkov <aekorotkov(at)gmail(dot)com> writes:
> > > >> >
> > > >> >> +static Oid *in_progress_list;
> > > >> >> +static int in_progress_list_len;
> > > >> >> +static int in_progress_list_maxlen;
> > > >> >
> > > >> > Is there any particular reason not to use pg_list.h for this?
> > > >> Sure. The type cache lookup has to be as much optimal as possible.
> > > >> Using an array and relating sequential access to it, we avoid memory
> > > >> allocations and deallocations 99.9% of the time. Also, quick access
> to
> > > >> the single element (which we will have in real life almost all of
> the
> > > >> time) is much faster than employing list machinery.
> > >
> > > Lists are actually dynamically resized arrays these days (see commit
> > > 1cff1b95ab6ddae32faa3efe0d95a820dbfdc164), not linked lists, so
> > > accessing arbitrary elements is O(1), not O(n). Just like this patch,
> > > the size is doubled (starting at 16) whenever array is full.
> > >
> > > > +1,
> > > > List with zero elements has to be NIL. That means continuous
> > > > allocations/deallocations.
> > >
> > > This however is a valid point (unless we keep a dummy zeroth element to
> > > avoid it, which is even uglier than open-coding the array extension
> > > logic), so objection withdrawn.
> >
> > OK, thank you!
> >
> > The attached revision fixes EXTRA_INSTALL in
> > src/test/modules/typcache/Makefile. Spotted off-list by Arthur
> > Zakirov.
>
> I've re-checked that regression tests pass with
> -DCLOBBER_CACHE_ALWAYS. Also did some grammar corrections for
> comments and commit message. I'm going to push this if no objections.
>
Thank you for working on this patch!
Looked through the patchset once more.

Patch 0001 (minor): "in the last" -> "after everything else" or "after
other TypeCacheEntry contents"

Patch 0002 looks ready to me.

Regards,
Pavel Borisov
Supabase