Re: Large backup size of pg_dump

On Wed, May 20, 2026 at 3:18 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"
>

1. Note that -Fp generates plain SQL files.
2. Where are you specifying the database name? Or is everything going into
"postgres"?
3. No need to specify the default port 5432.

> 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.
>

Is 16MB *that* big?

> 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?
>

Taking full backups every hour is suboptimal.

But if you *must*, then
pg_dump -Fp --compress=zstd $db > ${db}.sql.zst

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