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help / color / mirror / Atom feedFrom: Atsushi Torikoshi <[email protected]>
To: Jelte Fennema-Nio <[email protected]>
Cc: torikoshia <[email protected]>
Cc: Pgsql Hackers <[email protected]>
Cc: Tomas Vondra <[email protected]>
Subject: Re: RFC: Allow EXPLAIN to Output Page Fault Information
Date: Mon, 25 May 2026 21:17:56 +0900
Message-ID: <CAM6-o=BL59LgruKXm3DCjzFzvr7TTJPtryEPj51YeGMFrWO0EQ@mail.gmail.com> (raw)
In-Reply-To: <CAGECzQSOrmOTSyVHi1tkx9QDg9_PkVJudtdTH0B7ovHeZXtFLQ@mail.gmail.com>
References: <[email protected]>
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On Sun, May 24, 2026 at 6:50 PM Jelte Fennema-Nio <[email protected]> wrote:
>
> On Fri, 22 May 2026 at 18:07, Atsushi Torikoshi
> <[email protected]> wrote:
> > Updated the patch to clarify that the reported values include not only
> > the backend process executing the query, but also any parallel query
> > worker processes involved in the query.
>
> For PG19 Tomas added an IO option to EXPLAIN. I think it would be
> better to have the Storage IO tracking be enabled by the IO option,
> rather than the BUFFERS option.
Thank you for pointing that out.
I agree that having this under the IO option seems more intuitive.
One thing I am slightly concerned about, though, is that according to
the documentation, the IO option reports only I/O performed by scan
nodes:
> Include information on I/O performed by scan nodes providing such information.
In contrast, the information produced by this patch is based on
getrusage(), so it includes all Storage I/O performed by the backend
and parallel workers, not just scan nodes.
For example, it would also include temporary file I/O generated by
operations such as sorts that spill to disk when they exceed work_mem.
I suppose this could be clarified in the documentation, but I would be
interested to hear if anyone has concerns or objections about that
approach.
--
Regards,
Atsushi Torikoshi
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Subject: Re: RFC: Allow EXPLAIN to Output Page Fault Information
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