From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Jelte Fennema-Nio <postgres@jeltef.nl>,
        torikoshia <torikoshia@oss.nttdata.com>, pgsql-hackers@postgresql.org,
        rjuju123@gmail.com, Bruce Momjian <bruce@momjian.us>
Subject: Re: RFC: Allow EXPLAIN to Output Page Fault Information
In-reply-to: <myw76agwrlmisvamwbfl6ibxgwh5glzitydiwnfmtb5aui232i@274yxxtnbnsp>
References: <D6MJOHS7HZ80.3B17NDGUV6T47@jeltef.nl> <Z3LII9YEgp3kAZG-@momjian.us> <3861403.1735576764@sss.pgh.pa.us> <D6PENGW1PL79.266GQNPSMRIGA@jeltef.nl> <1f22794321b745549d54359d343e37b8@oss.nttdata.com> <D6V9GJ2LOLC5.1ZF3BWKKEBZWC@jeltef.nl> <CAM6-o=BE=oewSsdNKrbbNjR2muzQR49STXsuta+Wpq6CSyxTag@mail.gmail.com> <2c9d6eaf26df17bec13bb03bf1e9bcbb@oss.nttdata.com> <CAGECzQRvcLx44N3zd_DGCjY02XX4AqXX8mq4BiS8C9Froy+Jhg@mail.gmail.com> <CAGECzQQdc-k=M2fMCKa98kVZntc=6d3rpd6edt8Qs45cayfUeQ@mail.gmail.com> <myw76agwrlmisvamwbfl6ibxgwh5glzitydiwnfmtb5aui232i@274yxxtnbnsp>
Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Sun, 09 Feb 2025 12:59:27 -0500"
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Date: Sun, 09 Feb 2025 13:05:42 -0500
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Andres Freund <andres@anarazel.de> writes:
> I'm somewhat against this patch, as it's fairly fundamentally incompatible
> with AIO. There's no real way to get information in this manner if the IO
> isn't executed synchronously in process context...

Even without looking ahead to AIO, there's bgwriter, walwriter, and
checkpointer processes that all take I/O load away from foreground
processes.  I don't really believe that this will produce useful
numbers.

			regards, tom lane