From: Antonin Houska <ah@cybertec.at>
To: Tom Lane <tgl@sss.pgh.pa.us>
cc: Tomas Vondra <tomas@vondra.me>,
    Alvaro Herrera <alvherre@alvh.no-ip.org>,
    vignesh C <vignesh21@gmail.com>,
    Srinath Reddy Sadipiralla <srinath2133@gmail.com>,
    Amit Kapila <amit.kapila16@gmail.com>,
    Mihail Nikalayeu <mihailnikalayeu@gmail.com>,
    Matthias van de Meent <boekewurm+postgres@gmail.com>,
    Pg Hackers <pgsql-hackers@lists.postgresql.org>,
    Robert Treat <rob@xzilla.net>
Subject: Re: Adding REPACK [concurrently]
In-reply-to: <3074023.1775666853@sss.pgh.pa.us>
References: <202604060918.qw5ms7cbr2hz@alvherre.pgsql>
 <1c197f2d-49a2-4830-8dde-55867218b62d@vondra.me> <19118.1775645206@localhost>
 <3074023.1775666853@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
   message dated "Wed, 08 Apr 2026 12:47:33 -0400."
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <5806.1775717940.1@localhost>
Content-Transfer-Encoding: quoted-printable
Date: Thu, 09 Apr 2026 08:59:00 +0200
Message-ID: <5807.1775717940@localhost>
Archived-At: 
 <https://www.postgresql.org/message-id/5807.1775717940%40localhost>
Precedence: bulk

Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Antonin Houska <ah@cybertec.at> writes:

> > We already introduced this definition above in the function to suppres=
s this
> > kind of warning
> =

> >     union
> >     {
> > 	    alignas(int32) varlena hdr;
> > 	    char		data[sizeof(void *)];
> >     }			chunk_header;
> =

> > The problem on a 32-bit system probably is that sizeof(void *) is 4. W=
e need
> > some other constant. Maybe (sizeof(varlena) + 1) ...
> =

> This seems unnecessarily Rube Goldberg-ish already.

Indeed.

> Why not just
> =

> 	uint64	chunk_header;
> =

> It will not hurt anything if the variable has more-than-required
> alignment.  And it'd be better if it were the same size everywhere.

That's certainly better. Thanks.

-- =

Antonin Houska
Web: https://www.cybertec-postgresql.com