| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Simon Riggs <simon(dot)riggs(at)enterprisedb(dot)com>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, John Naylor <john(dot)naylor(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Lowering the ever-growing heap->pd_lower |
| Date: | 2021-08-04 22:29:03 |
| Message-ID: | CAH2-Wzmi4t_umu7F30A+MC=gVEcXNLGLuWD5_FOgvGGa4bbhww@mail.gmail.com |
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On Wed, Aug 4, 2021 at 7:39 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> How would it hurt?
>
> It's easy to see the harm caused by not shortening the line pointer
> array when it is possible to do so: we're using up space in the page
> that could have been made free. It's not so obvious to me what the
> downside of shortening it might be.
I think that that's probably true. That in itself doesn't seem like a
good enough reason to commit the patch.
Maybe this really won't be difficult for Matthias. I just want to see
some concrete testing, maybe with pgbench, or with an artificial test
case. Maybe something synthetic that shows a benefit measurable in
on-disk table size. Or at least the absence of any regressions.
Something.
--
Peter Geoghegan
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