| From: | "Core Studios Inc(dot)" <corestudiosinc(at)gmail(dot)com> |
|---|---|
| To: | Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Melanie Plageman <melanieplageman(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Konstantin Knizhnik <knizhnik(at)garret(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Alexander Kuzmenkov <akuzmenkov(at)timescale(dot)com> |
| Subject: | Re: Incorrect result of bitmap heap scan. |
| Date: | 2025-09-16 11:57:54 |
| Message-ID: | bd8b9bd6-d51f-466b-b578-47dedb2a0687@gmail.com |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Hello,
We noticed a sustained increased in IO Wait of read queries after
upgrading from 13.13 to 13.21. Eventually, we narrowed it down to a
spike in index_blocks_read of a certain table where Bitmap Heap Scans do
happen.
Do you think that this change (i.e. removing the optimization) could be
what caused this regression?
Thanks
On 3/5/25 1:12 PM, Matthias van de Meent wrote:
> On Sun, 2 Mar 2025 at 01:35, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Peter Geoghegan <pg(at)bowt(dot)ie> writes:
>>> Is everybody in agreement about committing and back patching this fix,
>>> which simply disables the optimization altogether?
>>> I myself don't see a better way, but thought I'd ask before proceeding
>>> with review and commit.
>> If you don't see a clear path forward, then "disable" is the only
>> reasonable choice for the back branches. Maybe we'll find a fix
>> in future, but it seems unlikely that it'd be back-patchable.
> Agreed.
>
> Here's patch v5 for the master branch (now up to f4694e0f), with no
> interesting changes other than fixing apply conflicts caused by
> bfe56cdf.
>
> Kind regards,
>
> Matthias van de Meent
> Neon (https://neon.tech)
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Robert Haas | 2025-09-16 12:02:21 | Re: [PATCH] Add tests for Bitmapset |
| Previous Message | Kouber Saparev | 2025-09-16 11:45:03 | Re: BF mamba failure |