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From: Guillaume Lelarge <guillaume@lelarge.info>
Date: Fri, 17 Jan 2025 16:34:31 +0100
Message-ID: <CAECtzeWsUE5EV_w8yRre28hZBUXPWE-fkFrqf7__B29jWAjP3Q@mail.gmail.com>
Subject: Re: Different Autovacuum Settings on Master and Replica in Streaming Replication
To: Franjo Stipanovic <fritzfs@gmail.com>
Cc: pgsql-general@lists.postgresql.org
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Hi,

Le ven. 17 janv. 2025 =C3=A0 15:38, Franjo Stipanovic <fritzfs@gmail.com> a
=C3=A9crit :

> Question regarding autovacuum settings in a PostgreSQL streaming
> replication setup. Specifically, I am curious about whether it is possibl=
e
> (and advisable) to have different values for the following settings on th=
e
> master and replica databases:
> - autovacuum_vacuum_scale_factor
> - autovacuum_analyze_scale_factor
>
> Can the above settings be configured differently on the master and replic=
a
> databases in a streaming replication setup? I just tested this on AWS RDS
> Postgres.
>

They could but it doesn't matter. VACUUM and ANALYZE aren't executed on
replicas because they are write operations, and you can't write on replicas=
.


> How would those different settings interact with replication, for example=
,
> if I apply change on master, would it be replicated to replica and overri=
de
> my replica setting?
>
Changes on the postgresq.conf file aren't replicated, but ALTER TABLE ...
(SET autovacuum...) are.

> I was expecting that this is not possible in streaming replication, only
> in logical replication.
>

You're right, it's not possible.


--=20
Guillaume.

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<div dir=3D"ltr"><div dir=3D"ltr">Hi,<br></div><br><div class=3D"gmail_quot=
e gmail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">Le=C2=A0ven.=
 17 janv. 2025 =C3=A0=C2=A015:38, Franjo Stipanovic &lt;<a href=3D"mailto:f=
ritzfs@gmail.com">fritzfs@gmail.com</a>&gt; a =C3=A9crit=C2=A0:<br></div><b=
lockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-le=
ft:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"><p>Questio=
n regarding autovacuum settings in a PostgreSQL streaming replication setup=
. Specifically, I am curious about whether it is possible (and advisable) t=
o have different values for the following settings on the master and replic=
a databases:<br>-=C2=A0autovacuum_vacuum_scale_factor<br>- autovacuum_analy=
ze_scale_factor</p><p>Can the above settings be configured differently on t=
he master and replica databases in a streaming replication setup? I just te=
sted this on AWS RDS Postgres.=C2=A0</p></div></blockquote><div><br></div><=
div>They could but it doesn&#39;t matter. VACUUM and ANALYZE aren&#39;t exe=
cuted on replicas because they are write operations, and you can&#39;t writ=
e on replicas.<br></div><div>=C2=A0<br></div><blockquote class=3D"gmail_quo=
te" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204=
);padding-left:1ex"><div dir=3D"ltr"><p>How would those different settings =
interact with replication, for example, if I apply change on master, would =
it be replicated to replica and override my replica setting?=C2=A0</p></div=
></blockquote><div>Changes on the postgresq.conf file aren&#39;t replicated=
, but ALTER TABLE ... (SET autovacuum...) are.<br></div><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
b(204,204,204);padding-left:1ex"><div dir=3D"ltr"><p>I was expecting that t=
his is not possible in streaming replication, only in logical replication.<=
/p></div></blockquote><div><br></div><div>You&#39;re right, it&#39;s not po=
ssible.</div><div><br></div><div><br></div></div><span class=3D"gmail_signa=
ture_prefix">-- </span><br><div dir=3D"ltr" class=3D"gmail_signature"><div =
dir=3D"ltr"><div><div dir=3D"ltr"><div>Guillaume.<br></div></div></div></di=
v></div></div>

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