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Re: Large backup size of pg_dump - Mailing list pgsql-general

From Priancka Chatz
Subject Re: Large backup size of pg_dump
Date
Msg-id CANnOdgbBJ_2Eizy48BkjbmjsHh2uUUxqX_pb6_zrpeMrtAAfJQ@mail.gmail.com
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In response to BUG #19569: Redundant outer DISTINCT adds Sort and Unique above EXCEPT  (PG Bug reporting form <noreply@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 AM Ertan Küçükoglu <ertan.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=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

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