Date: Thu, 8 Feb 2024 16:41:19 -0500
From: Stephen Frost <sfrost@snowman.net>
To: Ron Johnson <ronljohnsonjr@gmail.com>
Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
Subject: Re: pg_basebackup --wal-method=fetch
Message-ID: <ZcVKf0vByWDMVH5M@tamriel.snowman.net>
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Greetings,

* Ron Johnson (ronljohnsonjr@gmail.com) wrote:
> On Thu, Feb 8, 2024 at 12:48=E2=80=AFPM Magnus Hagander <magnus@hagander.=
net> wrote:
> > On Thu, Feb 8, 2024, 17:05 Ron Johnson <ronljohnsonjr@gmail.com> wrote:
> >> (PG 14, if it matters.)
> >>
> >> What's the purpose of fetch mode, as opposed to streaming mode?  Is it=
 a
> >> legacy of bygone days that just hasn't been deprecated, or is there
> >> something I don't understand from reading
> >> https://www.postgresql.org/docs/14/app-pgbasebackup.html?
> >
> > Your backup can go to a single file with it, which it can't do in
> > streaming. Which means it can also be sent through a pipe.
>=20
> But isn't the whole purpose of pg_basebackup (running it on Node B, when
> the database instance is Node A)?

Something seems missing from this question?

Being able to send through a pipe might allow someone to send directly
to a tape device or to a Bacula system or similar.

> > It also needs one connection instead of two to the server, if that's
> > limited.
>=20
> It's 2024, not 2011.  Who can't spare an extra connection?

Changing max_wal_senders requires a database-wide restart, so..

Not sure where you're going with this though.  Are you arguing that
fetch mode should be removed?  If so, why?  If that's not the angle,
then what is?  Would you suggest some better documentation of the
option?  I'm sure a proposal to improve the docs would be welcome, if
there's something confusing about them and this option.

Thanks!

Stephen

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