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From: "David G. Johnston" <david.g.johnston@gmail.com>
Date: Sun, 3 Aug 2025 21:47:48 -0700
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 <CAKFQuwafDdAKdYTWq_aC_=yXgUydCA__Aiim16C=ZT7Cr+M-vg@mail.gmail.com>
Subject: Re: Vacuuming System DBs like postgres, template1
To: OMPRAKASH SAHU <sahuop2121@gmail.com>
Cc: pgsql-admin@lists.postgresql.org
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On Sun, Aug 3, 2025 at 8:45=E2=80=AFPM OMPRAKASH SAHU <sahuop2121@gmail.com=
> wrote:

> On few large DBs we run vacuum analyze manually as well, and I do see few
> people vacuuming the template1 db or postgres db also
>
> So just wanted to know vacuum system dbs is required or not?
>
> Pretty sure the answer is yes - though letting auto-vacuum do it is
sufficient - since something has to update the catalog column that
indicates the oldest transaction the database is aware of.  There isn't a
value for that which means "everything has been frozen" since it doesn't
get updated in the normal course of activity.

David J.

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<div dir=3D"ltr"><div dir=3D"ltr"><div class=3D"gmail_default" style=3D"fon=
t-family:arial,helvetica,sans-serif"><span style=3D"font-family:Arial,Helve=
tica,sans-serif">On Sun, Aug 3, 2025 at 8:45=E2=80=AFPM OMPRAKASH SAHU &lt;=
<a href=3D"mailto:sahuop2121@gmail.com">sahuop2121@gmail.com</a>&gt; wrote:=
</span></div></div><div class=3D"gmail_quote gmail_quote_container"><blockq=
uote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1p=
x solid rgb(204,204,204);padding-left:1ex"><div dir=3D"auto"><div dir=3D"au=
to">On few large DBs we run vacuum analyze manually as well, and I do see f=
ew people vacuuming the template1 db or postgres db also=C2=A0</div><div di=
r=3D"auto"><br></div><div dir=3D"auto">So just wanted to know vacuum system=
 dbs is required or not?</div><div dir=3D"auto"><br></div></div></blockquot=
e><div><div class=3D"gmail_default" style=3D"font-family:arial,helvetica,sa=
ns-serif"></div><div class=3D"gmail_default" style=3D"font-family:arial,hel=
vetica,sans-serif">Pretty sure the answer is yes - though letting auto-vacu=
um do it is sufficient - since something has to update the catalog column t=
hat indicates the oldest transaction the database is aware of.=C2=A0 There =
isn&#39;t a value for that which means &quot;everything has been frozen&quo=
t; since it doesn&#39;t get updated in the normal course of activity.</div>=
</div><div class=3D"gmail_default" style=3D"font-family:arial,helvetica,san=
s-serif"><br></div><div class=3D"gmail_default" style=3D"font-family:arial,=
helvetica,sans-serif">David J.</div><div class=3D"gmail_default" style=3D"f=
ont-family:arial,helvetica,sans-serif"><br></div></div></div>

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