Feedback-ID: i0fe9450f:Fastmail
Date: Mon, 28 Aug 2023 10:53:52 +0900
From: Michael Paquier <michael@paquier.xyz>
To: "Imseih (AWS), Sami" <simseih@amazon.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>,
	Ian Lawrence Barwick <barwick@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>,
	"robertmhaas@gmail.com" <robertmhaas@gmail.com>
Subject: Re: pg_stat_get_backend_subxact() and backend IDs?
Message-ID: <ZOv+MHonWVgW/bpf@paquier.xyz>
References: <CAB8KJ=j-ACb3H4L9a_b3ZG3iCYDW5aEu3WsPAzkm2S7JzS1Few@mail.gmail.com>
 <20230824023206.GA1128857@nathanxps13.lan>
 <20230824025140.GB1128857@nathanxps13.lan>
 <20230824161913.GA1394441@nathanxps13.lan>
 <CAB8KJ=iWYvB1odjFRZybsPeUV8HUAiVVjY9RMHSdvWy1t77cLg@mail.gmail.com>
 <20230825153251.GA1593219@nathanxps13>
 <20230825192949.GA1917227@nathanxps13>
 <CF0C64D6-BB5C-4F84-98BB-8852A1C01A40@amazon.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="OKYliYMtQhPGQaBG"
Content-Disposition: inline
In-Reply-To: <CF0C64D6-BB5C-4F84-98BB-8852A1C01A40@amazon.com>
Archived-At: <https://www.postgresql.org/message-id/ZOv%2BMHonWVgW/bpf%40paquier.xyz>
Precedence: bulk


--OKYliYMtQhPGQaBG
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Fri, Aug 25, 2023 at 10:56:14PM +0000, Imseih (AWS), Sami wrote:
> > Here is a new version of the patch that avoids changing the names of the
> > existing functions. I'm not thrilled about the name
> > (pgstat_fetch_stat_local_beentry_by_backend_id), so I am open to
> > suggestions. In any case, I'd like to rename all three of the>
> > pgstat_fetch_stat_* functions in v17.
>=20
> Thanks for the updated patch.
>=20
> I reviewed/tested the latest version and I don't have any more comments.

FWIW, I find the new routine introduced by this patch rather
confusing.  pgstat_fetch_stat_local_beentry() and
pgstat_fetch_stat_local_beentry_by_backend_id() use the same=20
argument name for a BackendId or an int.  This is not entirely the
fault of this patch as pg_stat_get_backend_subxact() itself is
confused about "beid" being a uint32 or a BackendId.  However, I think
that this makes much harder to figure out that
pgstat_fetch_stat_local_beentry() is only here because it is cheaper=20
to do sequential scan of all the local beentries rather than a
bsearch() for all its callers, while
pgstat_fetch_stat_local_beentry_by_backend_id() is here because we
want to retrieve the local beentry matching with the *backend ID* with
the binary search().

I understand that this is not a fantastic naming, but renaming
pgstat_fetch_stat_local_beentry() to something like
pgstat_fetch_stat_local_beentry_by_{index|position}_id() would make
the difference much easier to grasp, and we should avoid the use of
"beid" when we refer to the *position/index ID* in
localBackendStatusTable, because it is not a BackendId at all, just a
position in the local array.
--
Michael

--OKYliYMtQhPGQaBG
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=chn0
-----END PGP SIGNATURE-----

--OKYliYMtQhPGQaBG--