> I don't think we need to support that case. I hope there are no clusters > in that state still in the wild, and you can work around it by upgrading > to 9.3.5 or above and letting autovacuum run. But I wonder if a > pre-upgrade check with a better error message would still be worthwhile.
I think we believe it is now highly unlikely to find instances of version 9.3; all users are advised to upgrade to the latest version first.
Thanks
On Tue, Nov 18, 2025 at 12:35 AM Heikki Linnakangas <hlinnaka@iki.fi> wrote:
Here's yet another patch version. I spent the day reviewing this in detail and doing little cleanups here and there. I squashed the commits and wrote a proper commit message.
One noteworthy refactoring is in pg_upgrade.c, to make it more clear (to me at least) how upgrade from version 9.2 and below now works. It was actually broken when I tested it. Not sure if I had broken it earlier or if it never worked, but in any case it works now.
I also tested upgrading a cluster from an old minor version, < 9.3.5, where the control file has a bogus oldestMultiXid==1 value (see commit b6a3444fa6). As expected, you get a "could not open file" error:
> Performing Upgrade > ------------------ > Setting locale and encoding for new cluster ok > ... > Deleting files from new pg_multixact/members ok > Deleting files from new pg_multixact/offsets ok > Converting pg_multixact files > could not open file "/home/heikki/pgsql.93stable/data/pg_multixact/offsets/0000": No such file or directory > Failure, exiting
I don't think we need to support that case. I hope there are no clusters in that state still in the wild, and you can work around it by upgrading to 9.3.5 or above and letting autovacuum run. But I wonder if a pre-upgrade check with a better error message would still be worthwhile.
Ashutosh, you were interested in reviewing this earlier. Would you have a chance to review this now, before I commit it? Alexander, Alvaro, would you have a chance to take a final look too, please?
