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Re: BUG: ReadStream look-ahead exhausts local buffers when effective_io_concurrency>=64 - Mailing list pgsql-hackers

From Feike Steenbergen
Subject Re: BUG: ReadStream look-ahead exhausts local buffers when effective_io_concurrency>=64
Date
Msg-id CAK_s-G2qY+D2X=cBoNBP3pxj+zmsqSjtZvmmXr8nE586f-0Fbw@mail.gmail.com
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In response to Re: BUG: ReadStream look-ahead exhausts local buffers when effective_io_concurrency>=64  (Eduard Stepanov <crtxcz@gmail.com>)
Responses Re: BUG: ReadStream look-ahead exhausts local buffers when effective_io_concurrency>=64
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Hi, all,

> On Tue, 10 Mar 2026 at 23:22, Induja Sreekanthan <indujas@google.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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