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From: Pavel Stehule <pavel.stehule@gmail.com>
Date: Wed, 19 Mar 2025 18:16:57 +0100
Message-ID: <CAFj8pRDhfOs5mDQNL7D7Z+CxX6ceXppQFLCOYPQKmLqH3BHotg@mail.gmail.com>
Subject: Re: size of attributes table is too big
To: =?UTF-8?Q?=C3=81lvaro_Herrera?= <alvherre@alvh.no-ip.org>
Cc: Siraj G <tosiraj.g@gmail.com>, pgsql-general@lists.postgresql.org
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st 19. 3. 2025 v 18:14 odes=C3=ADlatel =C3=81lvaro Herrera <alvherre@alvh.n=
o-ip.org>
napsal:

> Hello
>
> On 2025-Mar-19, Siraj G wrote:
>
> > I have a PG (v16) instance which is occupying around 1TB of storage. Ou=
t
> of
> > this, around 350GB is occupied by the table pg_catalog.pg_attribute.
> > Why is the catalog table's size so big?
>
> Heavy use of temp tables is a known cause of this.
>
> > I think this table must have tons of dead tuples. Please suggest to me =
if
> > we can purge any data/shrink the size of this table.
>
> Yeah, I'd also bet that there are tons of dead tuples, or just unused
> free space.  To purge it you would use VACUUM FULL, though that would
> need to lock all accesses to the table.
>
> Does your instance run with autovacuum disabled perchance?
>

or long unclosed transactions, maybe forgotten replication slots, ...

It is very strange so with this size it is still usable. Today hardware is
unbelievable strong

Regards

Pavel


>
> --
> =C3=81lvaro Herrera         PostgreSQL Developer  =E2=80=94
> https://www.EnterpriseDB.com/
> Bob [Floyd] used to say that he was planning to get a Ph.D. by the "green
> stamp method," namely by saving envelopes addressed to him as 'Dr. Floyd'=
.
> After collecting 500 such letters, he mused, a university somewhere in
> Arizona would probably grant him a degree.              (Don Knuth)
>
>
>

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote g=
mail_quote_container"><div dir=3D"ltr" class=3D"gmail_attr">st 19. 3. 2025 =
v=C2=A018:14 odes=C3=ADlatel =C3=81lvaro Herrera &lt;<a href=3D"mailto:alvh=
erre@alvh.no-ip.org">alvherre@alvh.no-ip.org</a>&gt; napsal:<br></div><bloc=
kquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:=
1px solid rgb(204,204,204);padding-left:1ex">Hello<br>
<br>
On 2025-Mar-19, Siraj G wrote:<br>
<br>
&gt; I have a PG (v16) instance which is occupying around 1TB of storage. O=
ut of<br>
&gt; this, around 350GB is occupied by the table pg_catalog.pg_attribute.<b=
r>
&gt; Why is the catalog table&#39;s size so big?<br>
<br>
Heavy use of temp tables is a known cause of this.<br>
<br>
&gt; I think this table must have tons of dead tuples. Please suggest to me=
 if<br>
&gt; we can purge any data/shrink the size of this table.<br>
<br>
Yeah, I&#39;d also bet that there are tons of dead tuples, or just unused<b=
r>
free space.=C2=A0 To purge it you would use VACUUM FULL, though that would<=
br>
need to lock all accesses to the table.<br>
<br>
Does your instance run with autovacuum disabled perchance?<br></blockquote>=
<div><br></div><div>or long unclosed transactions, maybe forgotten replicat=
ion slots, ...</div><div><br></div><div>It is very strange so with this siz=
e it is still usable. Today hardware is unbelievable strong</div><div><br><=
/div><div>Regards</div><div><br></div><div>Pavel <br></div><div>=C2=A0<br><=
/div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bo=
rder-left:1px solid rgb(204,204,204);padding-left:1ex">
<br>
-- <br>
=C3=81lvaro Herrera=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0PostgreSQL Developer=
=C2=A0 =E2=80=94=C2=A0 <a href=3D"https://www.EnterpriseDB.com/" rel=3D"nor=
eferrer" target=3D"_blank">https://www.EnterpriseDB.com/</a><br>
Bob [Floyd] used to say that he was planning to get a Ph.D. by the &quot;gr=
een<br>
stamp method,&quot; namely by saving envelopes addressed to him as &#39;Dr.=
 Floyd&#39;.<br>
After collecting 500 such letters, he mused, a university somewhere in<br>
Arizona would probably grant him a degree.=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 (Don Knuth)<br>
<br>
<br>
</blockquote></div></div>

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