Message-ID: <4e2cfc51d3933a1df28e212ccb0b90f39633422a.camel@cybertec.at>
Subject: Re: wal segment size
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Greg Sabino Mullane <htamfids@gmail.com>, Colin 't Hart
	 <colinthart@gmail.com>
Cc: PostgreSQL General <pgsql-general@lists.postgresql.org>
Date: Wed, 17 Dec 2025 18:58:45 +0100
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On Wed, 2025-12-17 at 12:21 -0500, Greg Sabino Mullane wrote:
> On Wed, Dec 17, 2025 at 11:10=E2=80=AFAM Colin 't Hart <colinthart@gmail.=
com> wrote:
> > Thanks Laurenz, that confirms what I was assuming. Archiving is via pgb=
ackrest
> > to a backup server, over SSH. Approx 750ms to archive each segment is c=
razy --
> > I'll check compression parameters too.
>=20
> Switch to archive-async =3D on. When doing that, the typical time drops t=
o 10ms or less.
> Also use a compress-type of lz4 or zst, which perform way better than the=
 default gz.
> If you are encrypting, that's a bottleneck you just have to deal with, no=
 shortcuts there. :)

I second that.  Asynchronous archiving in pgBackRest tends to work around t=
he problem.

> tl;dr try other things before messing with the WAL size. The current size=
 can work very
> well even on very large and very, very busy systems.

On the other hand, 16MB on a very busy system is somewhat ridiculous.
A somewhat bigger segment size may be appropriate.

Yours,
Laurenz Albe