MIME-Version: 1.0
References: <175578964049.806.14564779365418625473@wrigleys.postgresql.org>
 <568ff8638e011b2726d06a4b95124ec51ee1e5af.camel@cybertec.at>
 <a67687e233188a43a80b55c4ab8e1115bf2bd947.camel@cybertec.at>
 <aLTYpFWPT8v5JJh1@paquier.xyz>
 <CAFPkQKyGw+dnWZQM6QsqXWY_czqvvwMvF9Qfb4x916ZzHiRHeA@mail.gmail.com>
 <93913aeb398b264ca0dc781095d36d6ad2d3be71.camel@cybertec.at>
In-Reply-To: <93913aeb398b264ca0dc781095d36d6ad2d3be71.camel@cybertec.at>
From: Artem Gavrilov <artem.gavrilov@percona.com>
Date: Tue, 2 Sep 2025 11:22:15 +0200
Message-ID: 
 <CAFPkQKzuVjgEs=O40yw1LhBqRmKD4K+_6fHCGR9+j80f0wgoow@mail.gmail.com>
Subject: Re: Inaccurate statement about log shipping replication mode
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Michael Paquier <michael@paquier.xyz>, pgsql-docs@lists.postgresql.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: 
 <https://www.postgresql.org/message-id/CAFPkQKzuVjgEs%3DO40yw1LhBqRmKD4K%2B_6fHCGR9%2Bj80f0wgoow%40mail.gmail.com>
Precedence: bulk

Oh, sorry I made a typo, it should be "is always async". I was
referring to this statement in docs about cascading replication:
"Cascading replication is currently asynchronous". It sounds to me
like the whole replication setup is async (M -> U ->D), but it's only
the (U -> D) part that is always async. But probably it's a topic for
another thread.

My original problem was with the first sentence "It should be noted
that log shipping is asynchronous". I think your original suggestion
"It should be noted that by default, log shipping is asynchronous"
sounds good as it highlights from the beginning that there is some
variety.

On Tue, Sep 2, 2025 at 9:34=E2=80=AFAM Laurenz Albe <laurenz.albe@cybertec.=
at> wrote:
>
> On Mon, 2025-09-01 at 13:51 +0200, Artem Gavrilov wrote:
> > As I understand in configuration `Master
> > -> Upstream -> Downstream` replication between Master And Upstream
> > still can be synchronous, while between Upstream and Downstream is't
> > always async. Am I wrong here?
>
> I don't quite understand.  Sure, you can have synchronous replication
> between the master and upstream.  It is the "isn't always async" part
> that confuses me.  Do you mean that WAL can reach downstream before
> the master commits?  That is certainly the case.
>
> Yours,
> Laurenz Albe


--=20

Artem Gavrilov
Senior Software Engineer, Percona

artem.gavrilov@percona.com