| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Lowering the ever-growing heap->pd_lower |
| Date: | 2022-04-08 19:04:37 |
| Message-ID: | CA+TgmoZbHjMMFs1=_vqUxkFE8_+o9TtiRwA8r+sp-4J32z+nsQ@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Fri, Apr 8, 2022 at 12:57 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> What do you mean about wasting space? Wasting space on the stack? I
> can't imagine you meant wasting space on the page, since being able to
> accomodate more items on each heap page seems like it would be
> strictly better, barring any unintended weird FSM issues.
I meant wasting space in the page. I think that's a real concern.
Imagine you allowed 1000 line pointers per page. Each one consumes 2
bytes. So now you could have ~25% of each page in the table storing
dead line pointers. That sounds awful, and just running VACUUM won't
fix it once it's happened, because the still-live line pointers are
likely to be at the end of the line pointer array and thus truncating
it won't necessarily be possible.
--
Robert Haas
EDB: http://www.enterprisedb.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Tom Lane | 2022-04-08 19:05:25 | Re: Frontend error logging style |
| Previous Message | Peter Geoghegan | 2022-04-08 18:57:53 | Re: Lowering the ever-growing heap->pd_lower |