Feedback-ID: i0fe9450f:Fastmail
Date: Fri, 12 Jun 2026 11:44:47 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Xuneng Zhou <xunengzhou@gmail.com>
Cc: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>,
	"Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
	Alexander Lakhin <exclusion@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: t/035_standby_logical_decoding.pl might fail on attempt to read
 wrong timeline
Message-ID: <aityn4rQkc7fv8qT@paquier.xyz>
References: 
 <CABPTF7WmLKOJcSPod7zT2hynUFQcUs0VoQyR-p=XFsafvmGm7g@mail.gmail.com>
 <CABPTF7U_B9pdC563fFONQLX_FXCZtxZgM+jN9snzMVg9b9MRfg@mail.gmail.com>
 <aibQB2f9h3nYeg/2@bdtpg>
 <CABPTF7XGDgnB97fBUQb+Tm=5NnAzS1iKTWcJTePpGinL1ZAxWQ@mail.gmail.com>
 <CABPTF7VovNWnH=dG_A=e6xkMYt11ubbj935Ymfky55cXcWcrrA@mail.gmail.com>
 <aifyiJG3uiJzCYTB@bdtpg>
 <CABPTF7XAb7ExE-7qSsKgSw3K0hfsNPzXuupQ1aJ8zXOgZ4tPNw@mail.gmail.com>
 <aimeoNYE93VLiQHt@bdtpg>
 <aioMFYcZhLB6urla@paquier.xyz>
 <CABPTF7WSpNOYu84fjGH2t56BctRzVD7t8WqhgvML2DRh8Vtfog@mail.gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
	protocol="application/pgp-signature"; boundary="siFkxeHz0tnCZ8sK"
Content-Disposition: inline
In-Reply-To: 
 <CABPTF7WSpNOYu84fjGH2t56BctRzVD7t8WqhgvML2DRh8Vtfog@mail.gmail.com>
Archived-At: 
 <https://www.postgresql.org/message-id/aityn4rQkc7fv8qT%40paquier.xyz>
Precedence: bulk


--siFkxeHz0tnCZ8sK
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Fri, Jun 12, 2026 at 08:57:05AM +0800, Xuneng Zhou wrote:
> On Thu, Jun 11, 2026 at 9:15=E2=80=AFAM Michael Paquier <michael@paquier.=
xyz> wrote:
>> read_local_xlog_page_guts() does not only impact SQL-callable logirep
>> functions, even it is the spot that should be hit most of the time
>> (again, the RecoveryInProgress() vs promotion window is super narrow).
>> At quick glance, things are:
>> - walinspect.
>> - Slot advance.
>> - Slot creation (?), but it feels even narrower.
>=20
> Yeah, it is used for two-phase commit as well. The usage of it is
> broader than I observed before. Repack worker also make use of it.

Repack workers cannot work on standbys, and for 2PC files we have the
guarantee of a file on disk if the WAL is gone, so they should be
basically irrelevant here.  That's why I did not mention them.  :)

Everything's now done.  I was pondering about v14 and v15 for a bit
for the second patch regarding pg_walinspect (or slot operations), but
I could not get excited about these branches.  pg_walinspect is less
used, and slots have much more uses on standbys since v16~, so
expanding that further down feels meh.
--
Michael

--siFkxeHz0tnCZ8sK
Content-Type: application/pgp-signature; name=signature.asc

-----BEGIN PGP SIGNATURE-----
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=xm3m
-----END PGP SIGNATURE-----

--siFkxeHz0tnCZ8sK--