public inbox for [email protected]
help / color / mirror / Atom feedFrom: Laurenz Albe <[email protected]>
To: Ashish Mukherjee <[email protected]>
To: [email protected]
Subject: Re: Downgrade pgsql 17 to pgsql 12 question
Date: Fri, 26 Sep 2025 16:27:33 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CACgMzfxO7h+Bj4T8rjTV=trM3+Uw=jOAcUE+0Kimv4DSAVU1JA@mail.gmail.com>
References: <CACgMzfxO7h+Bj4T8rjTV=trM3+Uw=jOAcUE+0Kimv4DSAVU1JA@mail.gmail.com>
On Fri, 2025-09-26 at 17:48 +0530, Ashish Mukherjee wrote:
> 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.
>
> 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?
Yes, there is the risk that the restore will fail.
Downgrading is not supported.
That's why the best way to do it is a plain format dump: you can edit the
dump file to manually fix any errors.
I am surprised that you think that restoring a plain format dump would
be significantly slower than restoring a different format (unless you are
talking about parallel restore with -j).
> 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.
Anything can happen...
> When I do dump/restore like this for a test table, I get the following errors
> during restore but the table gets restored fine.
>
> pg_restore: error: while PROCESSING TOC:
> error: pg_restore: error: pg_restore: from TOC entry 17168; 1259 58572315 TABLE pkgs s14
> pg_restore: error: pg_restore: pg_restore: pg_restore: from TOC entry 17168; 1259 58572315 TABLE pkgs s14
> pg_restore: error: pg_restore: from TOC entry 17168; 1259 58572315 TABLE pkgs s14
> pg_restore: error: pg_restore: from TOC entry 17168; 1259 58572315 TABLE pkgs s14
> error: from TOC entry 17168; 1259 58572315 TABLE pkgs s14
> pg_restore: warning: errors ignored on restore: 2
>
> pkgs is the table and s14 is my database
There should be more: the actual error messages. These will give you a clue.
Yours,
Laurenz Albe
view thread (5+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected], [email protected]
Subject: Re: Downgrade pgsql 17 to pgsql 12 question
In-Reply-To: <[email protected]>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox