Re: Large backup size of pg_dump

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 AM Ertan Küçükoglu <ertan(dot)kucukoglu(at)gmail(dot)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=app -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 to
> make the hourly backup size smaller?
>
> Thanks & Regards,
> Ertan
>