MIME-Version: 1.0
References: 
 <CAOj6k6dy2CRVA6Lsb5N59zE-7KNVKt=oYwWyg8ULK8zOOY8e7A@mail.gmail.com>
 <CAOj6k6dkseVvZzmEAWvBd6twZsCU0DbN+qeM7CoDuMM3r9doiw@mail.gmail.com>
 <CAOj6k6eSsQ_PTUTxW0upn6wp7tzbvQwqkQco-=+majwX8p6JJg@mail.gmail.com>
 <4c70b0f6-5aba-464c-b145-464a620c1222@eisentraut.org>
 <aUOgmypuun0rc2xO@paquier.xyz>
 <CAOj6k6fxs0Bwjr34W4aURzFPta0DTGLN-1ic-U+-M_EqJ+Wd8A@mail.gmail.com>
 <aUSDs7SaEcOa65gD@paquier.xyz>
In-Reply-To: <aUSDs7SaEcOa65gD@paquier.xyz>
From: Robert Treat <rob@xzilla.net>
Date: Wed, 24 Dec 2025 11:50:48 -0500
Message-ID: 
 <CABV9wwOdeFHHNnw+rUsVnFek-oqwsJnJX9KFG6AT5Yqz5RA_vg@mail.gmail.com>
Subject: Re: Fwd: [PATCH] Add zstd compression for TOAST using extended header
 format
To: Michael Paquier <michael@paquier.xyz>
Cc: Dharin Shah <dharinshah95@gmail.com>,
 Peter Eisentraut <peter@eisentraut.org>,
	pgsql-hackers@lists.postgresql.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: 
 <https://www.postgresql.org/message-id/CABV9wwOdeFHHNnw%2BrUsVnFek-oqwsJnJX9KFG6AT5Yqz5RA_vg%40mail.gmail.com>
Precedence: bulk

On Thu, Dec 18, 2025 at 5:44=E2=80=AFPM Michael Paquier <michael@paquier.xy=
z> wrote:
> On Thu, Dec 18, 2025 at 10:44:22PM +0100, Dharin Shah wrote:
> > I'll share the detailed benchmark script with the next patch revision. =
But
> > also a potential path forward could be that we could just fully replace
> > pglz (can bring it up later in different thread)
>
> I don't think that we will ever be able to remove pglz.  It would be
> nice, as final result of course, but I also expect that not being able
> to decompress pglz data is going to lead to a lot of user pain.  That
> would be also very expensive to check at upgrade for large instances.
>

Agreed that I can't see pglz being removed any time soon, if ever.
Thinking through what a conversion process would look like seems
unwieldy at best, so I think we definitely need it for backwards
compatibility, plus I think it is useful to have a self-contained
option. I'd almost suggest we should look at replacing lz4, but I
don't think that is significantly easier, it just has a smaller, more
invested, blast radius. That said, I do suspect ztsd could quickly
become a popular recommendation and/or default among users /
consultants / service providers.

Robert Treat
https://xzilla.net