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From: Priancka Chatz <pc9926@gmail.com>
Date: Wed, 20 May 2026 13:23:09 +0200
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Subject: Re: Large backup size of pg_dump
To: =?UTF-8?B?RXJ0YW4gS8O8w6fDvGtvZ2x1?= <ertan.kucukoglu@gmail.com>
Cc: pgsql-general@lists.postgresql.org
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When you store large objects, the actual data resides on pg_largeobject
table (https://www.postgresql.org/docs/current/catalog-pg-largeobject.html)=
.
So your "app" table might not be the only thing to exclude in your dump.

Regards,
Priyanka Chatterjee

On Wed, May 20, 2026 at 9:18=E2=80=AFAM Ertan K=C3=BC=C3=A7=C3=BCkoglu <ert=
an.kucukoglu@gmail.com>
wrote:

> Hello,
>
> I am using PostgreSQL 18.4 x64 on Windows Server 2022. There is a very
> small single database in the cluster.
>
> There are hourly pg_dump backups scheduled and database backup size is
> around 10GB.
>
> command line is like below
> pg_dump.exe -p 5432 -U dbuser --exclude-table=3Dapp -F p -b -c -f
> "hourly.bak"
>
> When I check the cluster directory size it is 4.1 GB.
>
> Database has one BLOB saved in a single record and it is 16MB in size and
> that is in the "app" table which is excluded from the backup file.
>
> I didn't understand about 2.5 times bigger backup sizes than the total
> cluster size. I do not know what to check either. Is there a way for me t=
o
> make the hourly backup size smaller?
>
> Thanks & Regards,
> Ertan
>

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<div dir=3D"ltr">When you store large objects, the actual data resides on p=
g_largeobject table (<a href=3D"https://www.postgresql.org/docs/current/cat=
alog-pg-largeobject.html">https://www.postgresql.org/docs/current/catalog-p=
g-largeobject.html</a>). So your &quot;app&quot; table might not be the onl=
y thing to exclude in your dump.<div><br></div><div>Regards,</div><div>Priy=
anka Chatterjee</div></div><br><div class=3D"gmail_quote gmail_quote_contai=
ner"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, May 20, 2026 at 9:18=E2=
=80=AFAM Ertan K=C3=BC=C3=A7=C3=BCkoglu &lt;<a href=3D"mailto:ertan.kucukog=
lu@gmail.com">ertan.kucukoglu@gmail.com</a>&gt; wrote:<br></div><blockquote=
 class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px so=
lid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Hello,<div><br></di=
v><div>I am using PostgreSQL 18.4 x64 on Windows=C2=A0Server 2022. There is=
 a very small single database in the cluster.</div><div><br></div><div>Ther=
e are hourly pg_dump backups scheduled and database backup size is around 1=
0GB.</div><div><br></div><div>command line is like below</div><div>pg_dump.=
exe -p 5432 -U dbuser --exclude-table=3Dapp -F p -b -c -f &quot;hourly.bak&=
quot;</div><div><br></div><div>When I check the cluster directory size it i=
s 4.1 GB.</div><div><br></div><div>Database has one BLOB saved in a single =
record and it is 16MB in size and that is in the &quot;app&quot; table whic=
h is excluded from the backup file.</div><div><br></div><div>I didn&#39;t u=
nderstand about 2.5 times bigger backup sizes than the total cluster size. =
I do not know what to check either. Is there a way for me to make the hourl=
y backup size smaller?</div><div><br></div><div>Thanks &amp;=C2=A0Regards,<=
/div><div>Ertan</div></div>
</blockquote></div>

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