Message-ID: <9720a2c9245df13906591abc4ede6cb10db32ab3.camel@cybertec.at>
Subject: Re: AW: [Extern] Re: promote a deferred standby without applying
 WALs
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: "Zwettler Markus (OIZ)" <Markus.Zwettler@zuerich.ch>,
	"pgsql-admin@lists.postgresql.org"
	 <pgsql-admin@lists.postgresql.org>
Date: Tue, 16 Jul 2024 11:21:32 +0200
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On Tue, 2024-07-16 at 09:01 +0000, Zwettler Markus (OIZ) wrote:
> > On Tue, 2024-07-16 at 08:04 +0000, Zwettler Markus (OIZ) wrote:
> > > I have a standby database running 3 hours behind the primary (recover=
y_min_apply_delay =3D '3h').
> > >=20
> > > In case of a logical error on the primary I want to promote the stand=
by database
> > > which still has correct data.
> > >=20
> > > The standby should not apply any more WAL in that case.
> > >=20
> > > It seems that this can only be done manually:
> > >=20
> > > =C2=A0=C2=A0=C2=A01. pg_ctl stop
> > > =C2=A0=C2=A0=C2=A02. rm -rf standby.signal
> > > =C2=A0=C2=A0=C2=A03. set primary_conninfo =3D ''
> > > =C2=A0=C2=A0=C2=A04. pg_ctl start
> > >=20
> > > Is there no single command on this?
> >=20
> > Perhaps this could be the single command:
> >=20
> > =C2=A0=C2=A0psql -c "ALTER SYSTEM SET recovery_target_time =3D '2024-07=
-16 12:00:00'" -c
> > "SELECT pg_reload_conf()"
>=20
> setting recovery_target_time + reload would be step 0 in that case, befor=
e stop/start. correct?

No, that would be the only step.  A restart is not necessary, and PostgreSQ=
L will
automatically promote the standby when the target time is reached (if you s=
et
"recovery_target_action" to "promote").

Yours,
Laurenz Albe

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