MIME-Version: 1.0
References: 
 <CAAKRu_YX0NP_yhXvPnvDRjVxxprsRBM-_MZzAJskfMydMQ=ETA@mail.gmail.com>
 <CA+TgmoYgCs=SEsohP6Z6R3KKsGaqFqvqxH8vQ_-nY4t+7rK8jg@mail.gmail.com>
 <CAAKRu_ZP-3=SaZykpwDBMJOdUKyW3Wm5JZfPFRR3L5Ac8ouq4w@mail.gmail.com>
 <CAAKRu_bgkOQqu3K5n4YLRsNBZqJ9Rjg80ROqgKSr2UGz4b5hUg@mail.gmail.com>
 <2wk7jo4m4qwh5sn33pfgerdjfujebbccsmmlownybddbh6nawl@mdyyqpqzxjek>
 <CAAKRu_YR-COJ9aGnMUQqt5yoWmUBjikqrd4jGNZYouHaXpis9g@mail.gmail.com>
 <CALdSSPhiCwJwWwgJP1NmqRmnp9RS2tGOBY0gQrfLCbB+OS5_KQ@mail.gmail.com>
 <CAAKRu_YS+Ocm=OzMaZnG4egFiE9v4VYfZ25DXd6jbwegqmGYbQ@mail.gmail.com>
 <CAAKRu_ZGZSqhGt-RcmmfiSheC+1fjQdxy6_+oM-1jMn8hyVptQ@mail.gmail.com>
 <CALdSSPg+B8RTzTXhJvCcKJBqgzhPZkq0E2oqxQdv74ZNZOMVzg@mail.gmail.com>
 <CAAKRu_Zha7HcdQBv8tTtQrcry5332J6kHnOc1X=TT03LzUXDow@mail.gmail.com>
 <CAAKRu_amF00f2T_H8N6pbbe75C22EeX1OqA=svpj8LNO1sdUuw@mail.gmail.com>
 <bfc015b8-eaea-423d-9a09-1d39c4fe9947@eisentraut.org>
 <CAAKRu_bsDnYW-8PLncPvqb5ndcUriCL9pBdimNkYWTQV4sxO-A@mail.gmail.com>
 <fb97d0ae-a0bc-411d-8a87-f84e7e146488@eisentraut.org>
In-Reply-To: <fb97d0ae-a0bc-411d-8a87-f84e7e146488@eisentraut.org>
From: Melanie Plageman <melanieplageman@gmail.com>
Date: Tue, 16 Dec 2025 11:07:17 -0500
Message-ID: 
 <CAAKRu_bHpHthLdBrvLGhJsTLLe6zkPk5Q9pnBLrOdObUBZiwDg@mail.gmail.com>
Subject: Re: eliminate xl_heap_visible to reduce WAL (and eventually set VM
 on-access)
To: Peter Eisentraut <peter@eisentraut.org>
Cc: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>,
	Andrey Borodin <x4mmm@yandex-team.ru>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
 Heikki Linnakangas <hlinnaka@iki.fi>,
	Kirill Reshke <reshkekirill@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: 
 <https://www.postgresql.org/message-id/CAAKRu_bHpHthLdBrvLGhJsTLLe6zkPk5Q9pnBLrOdObUBZiwDg%40mail.gmail.com>
Precedence: bulk

On Tue, Dec 16, 2025 at 7:18=E2=80=AFAM Peter Eisentraut <peter@eisentraut.=
org> wrote:
>
> You are not modifying deadoffsets in prune_freeze_setup(), but you are
> assigning its address to a pointer variable that is not const-qualified,
> and so it could be used to modify it later on.
>
> A caller to prune_freeze_setup() that sees the signature const
> PruneFreezeResult *presult could pass a pointer to a PruneFreezeResult
> object that is notionally in read-only memory.  But through the
> non-const-qualified pointer you could later modify the pointed-to
> memory, which would be invalid.  The point of propagating the qualifiers
> is to prevent that at compile time.

Thanks for the explanation. I've committed your proposed fix.

- Melanie