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Message-ID: <d061e898-9a81-411b-9ecf-fb928321caff@aklaver.com>
Date: Fri, 26 Sep 2025 08:10:03 -0700
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Subject: Re: Downgrade pgsql 17 to pgsql 12 question
To: Ashish Mukherjee <ashish.mukherjee@gmail.com>,
 pgsql-general@postgresql.org
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From: Adrian Klaver <adrian.klaver@aklaver.com>
In-Reply-To: <CACgMzfxO7h+Bj4T8rjTV=trM3+Uw=jOAcUE+0Kimv4DSAVU1JA@mail.gmail.com>
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On 9/26/25 05:18, Ashish Mukherjee wrote:
> Hello,
> 
> I have a strange requirement to downgrade from pgsql 17 to pgsql 12. 
> This is because we found in production certain incompatibilities between 
> both versions for our database. It should have been caught in testing 
> but was not.
> 

What are the incompatibilities?

Might be easier to deal with those then doing the below.

> The clean way seems to be text file dump and restore but this would be 
> too huge and too slow for our database of 3T. If I use pg_dump v17 and 
> then restore with pg_restore v 17 on a pgsql v12 database, is there any 
> risk? I tried a small test with a bunch of tables and it worked, but am 
> wondering about the pitfalls. I am restoring from the directory format dump.
> 
> When I do dump/restore like this for a test table, I get the following 
> errors during restore but the table gets restored fine.

> Any input would be appreciated.
> 
> Regards,
> Ashish


-- 
Adrian Klaver
adrian.klaver@aklaver.com