Date: Fri, 7 Aug 2026 22:27:04 +0200
From: Christoph Berg <myon@debian.org>
To: Tomas Vondra <tomas@vondra.me>
Cc: Andrey Borodin <x4mmm@yandex-team.ru>, Ken Marshall <ktm@rice.edu>,
	Hannu Krosing <hannuk@google.com>,
	Andreas Karlsson <andreas@proxel.se>,
	wenhui qiu <qiuwenhuifx@gmail.com>,
	Laurenz Albe <laurenz.albe@cybertec.at>,
	Andres Freund <andres@anarazel.de>,
	Jelte Fennema-Nio <postgres@jeltef.nl>,
	Michael Paquier <michael@paquier.xyz>,
	Japin Li <japinli@hotmail.com>, Fujii Masao <masao.fujii@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>,
	John Naylor <johncnaylorls@gmail.com>
Subject: Re: WAL compression setting after PostgreSQL LZ4 default change
Message-ID: <anY_mPKGboIMTFS2@msg.df7cb.de>
Mail-Followup-To: Christoph Berg <myon@debian.org>,
	Tomas Vondra <tomas@vondra.me>,
	Andrey Borodin <x4mmm@yandex-team.ru>, Ken Marshall <ktm@rice.edu>,
	Hannu Krosing <hannuk@google.com>,
	Andreas Karlsson <andreas@proxel.se>,
	wenhui qiu <qiuwenhuifx@gmail.com>,
	Laurenz Albe <laurenz.albe@cybertec.at>,
	Andres Freund <andres@anarazel.de>,
	Jelte Fennema-Nio <postgres@jeltef.nl>,
	Michael Paquier <michael@paquier.xyz>,
	Japin Li <japinli@hotmail.com>, Fujii Masao <masao.fujii@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>,
	John Naylor <johncnaylorls@gmail.com>
References: 
 <CAMT0RQT2JKFmiEnVUzGex2nmgvoYCegVD_+71e17o1p0fyHx8Q@mail.gmail.com>
 <97667b29-9b73-4418-93de-e1928c236b66@vondra.me>
 <3ebe2c65-7fe5-49cb-ad49-84c1d0cf567b@vondra.me>
 <CAMT0RQS_d-29QS50SYH=u15tPWrnb45ahJwi+D-5Yo6phO4mTw@mail.gmail.com>
 <anSfQumImev8kDKI@customer.dllstxx1.isp.starlink.com>
 <da2389df-05a0-4ba7-8284-4344d31b5882@vondra.me>
 <1a39cbd6-6528-4f04-8d19-54e3790f006a@vondra.me>
 <A0D6CED4-F9FB-4A96-A433-E1C3B3CE501E@yandex-team.ru>
 <438ce1b2-54d5-4730-99aa-47b9b8f97a19@vondra.me>
 <18d632e6-6fa9-42fc-9dda-bad166374aa5@vondra.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <18d632e6-6fa9-42fc-9dda-bad166374aa5@vondra.me>
Archived-At: 
 <https://www.postgresql.org/message-id/anY_mPKGboIMTFS2%40msg.df7cb.de>
Precedence: bulk

Re: Tomas Vondra
> The question is what does this mean for this thread, i.e. for the
> question what should 'on' translate to. I still think zstd seems like a
> better default, despite this one result where lz4 does a bit better.
> Especially if we know it the difference can be mostly eliminated.

To me, this doesn't read like a question but a confirmation that zstd
is the correct pick. They are close now, we tend to prefer zstd, and
now we know how to make zstd even better in PG 20, then it looks clear
that zstd is the "on" to go so we aren't switching twice.

(As said above I don't think "PG 19: toast lz4, wal zstd" is bad, the
important bit is "PG 19 is switching toast and wal away from pglz",
that is the message we should put into the release notes.)

Christoph