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From: vignesh C <vignesh21@gmail.com>
Date: Wed, 11 Jan 2023 22:02:37 +0530
Message-ID: <CALDaNm0ikdqV2b3wEFCkrTdSv2uGbuyqB2J2dxp=E5+ssXY9Ww@mail.gmail.com>
Subject: Re: pg_stat_bgwriter.buffers_backend is pretty meaningless (and more?)
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Lukas Fittl <lukas@fittl.com>, 
	Justin Pryzby <pryzby@telsasoft.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, 
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Magnus Hagander <magnus@hagander.net>, 
	Pg Hackers <pgsql-hackers@postgresql.org>, Thomas Munro <thomas.munro@gmail.com>, 
	Maciek Sakrejda <m.sakrejda@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Archived-At: <https://www.postgresql.org/message-id/CALDaNm0ikdqV2b3wEFCkrTdSv2uGbuyqB2J2dxp%3DE5%2BssXY9Ww%40mail.gmail.com>
Precedence: bulk

On Tue, 10 Jan 2023 at 02:41, Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> Attached is v45 of the patchset. I've done some additional code cleanup
> and changes. The most significant change, however, is the docs. I've
> separated the docs into its own patch for ease of review.
>
> The docs patch here was edited and co-authored by Samay Sharma.
> I'm not sure if the order of pg_stat_io in the docs is correct.
>
> The significant changes are removal of all "correspondence" or
> "equivalence"-related sections (those explaining how other IO stats were
> the same or different from pg_stat_io columns).
>
> I've tried to remove references to "strategies" and "Buffer Access
> Strategy" as much as possible.
>
> I've moved the advice and interpretation section to the bottom --
> outside of the table of definitions. Since this page is primarily a
> reference page, I agree with Samay that incorporating interpretation
> into the column definitions adds clutter and confusion.
>
> I think the best course would be to have an "Interpreting Statistics"
> section.
>
> I suggest a structure like the following for this section:
>     - Statistics Collection Configuration
>     - Viewing Statistics
>     - Statistics Views Reference
>     - Statistics Functions Reference
>     - Interpreting Statistics
>
> As an aside, this section of the docs has some other structural issues
> as well.
>
> For example, I'm not sure it makes sense to have the dynamic statistics
> views as sub-sections under 28.2, which is titled "The Cumulative
> Statistics System."
>
> In fact the docs say this under Section 28.2
> https://www.postgresql.org/docs/current/monitoring-stats.html
>
> "PostgreSQL also supports reporting dynamic information about exactly
> what is going on in the system right now, such as the exact command
> currently being executed by other server processes, and which other
> connections exist in the system. This facility is independent of the
> cumulative statistics system."
>
> So, it is a bit weird that they are defined under the section titled
> "The Cumulative Statistics System".
>
> In this version of the patchset, I have not attempted a new structure
> but instead moved the advice/interpretation for pg_stat_io to below the
> table containing the column definitions.

For some reason cfbot is not able to apply this patch as in [1],
please have a look and post an updated patch if required:
=== Applying patches on top of PostgreSQL commit ID
3c6fc58209f24b959ee18f5d19ef96403d08f15c ===
=== applying patch
./v45-0001-pgindent-and-some-manual-cleanup-in-pgstat-relat.patch
patching file src/backend/storage/buffer/bufmgr.c
patching file src/backend/storage/buffer/localbuf.c
patching file src/backend/utils/activity/pgstat.c
patching file src/backend/utils/activity/pgstat_relation.c
patching file src/backend/utils/adt/pgstatfuncs.c
patching file src/include/pgstat.h
patching file src/include/utils/pgstat_internal.h
=== applying patch ./v45-0002-pgstat-Infrastructure-to-track-IO-operations.patch
gpatch: **** Only garbage was found in the patch input.

[1] - http://cfbot.cputube.org/patch_41_3272.log

Regards,
Vignesh