| From: | Feike Steenbergen <feikesteenbergen(at)gmail(dot)com> |
|---|---|
| To: | Eduard Stepanov <crtxcz(at)gmail(dot)com> |
| Cc: | Induja Sreekanthan <indujas(at)google(dot)com>, pgsql-hackers(at)postgresql(dot)org, Simhachala Sasikanth Gottapu <simhachala(at)google(dot)com>, Vishal Bagga <vishalbagga(at)google(dot)com>, Madhukar <madhukarprasad(at)google(dot)com>, Shihao Zhong <shihaozhong(at)google(dot)com>, Yi Ding <yidin(at)google(dot)com>, Hardik Singh Negi <hardiksnegi(at)google(dot)com> |
| Subject: | Re: BUG: ReadStream look-ahead exhausts local buffers when effective_io_concurrency>=64 |
| Date: | 2026-05-06 12:24:38 |
| Message-ID: | CAK_s-G2qY+D2X=cBoNBP3pxj+zmsqSjtZvmmXr8nE586f-0Fbw@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi, all,
> On Tue, 10 Mar 2026 at 23:22, Induja Sreekanthan <indujas(at)google(dot)com>
wrote:
> >
> > Hi,
> >
> > I found an issue where Postgres (with effective_io_concurrency of 64 or
higher) runs out of local buffers during a sequential scan on a temporary
table with TOAST data.
> >
Just to confirm, I have a production db (20TB, high concurrency, lot's of
updates/merges) that
is a heavy user of temp tables running into this as well with
io_method='io_uring'.
This started after having upgraded PostgreSQL 18 (from 17).
For now, the problem disappears again when switching to io_method='worker'
Thank you for providing the patches,
kind regards,
Feike Steenbergen
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