Database upgrade Pg11 to Pg12 issues

Hi

I have upgraded many Pg databases from 9 to 10 to 11 using the Ubuntu
pg_upgradecluster command (wrapper to pg_update) without issues, however
today I upgraded a DB from 11 to 12.

Using the syntax

*/pg_upgradecluser -k -m upgrade 11 main/*

using the latest 12.5 binaries all appeared to work well, and for a 330G
DB this took 2 minutes. On starting the DB using

systemctl start postgresql(at)12(dot)service

the DB started, but the screen showed the default directory was
*//var/lib/postgresql/11/main/*. Checking the open database with

/*show data_directory; */gave /*/var/lib/postgresql/12/main*/

Then using /*lsof | grep '11/main'*/ gave no files, but/*lsof | grep
'12/main'*/ gave over 30K files, Checking the directory sizes suggests
that 11/main is 300G and 12/main is 40G

So all appears OK, with files hard linked between 11/main and 12/main,
and I assume the issue relates to the PGDATA/postgresql.auto.conf file
being just copied from the original 11/main with data_directory being
set to /var/lib/postgresql/11/main.

If I where to run /*pg_dropcluster 11 main*/ to remove the old database
and conf files, will this destroy my running Pg12 database with hard
linked files in 11/main and 12/main? In theory it shouldn't and files
from 11/main and 12/main will all be under 12/main, I just have doubts.

Is there an easy way to tidy this up?

Simon

--
Simon Windsor

Eml: simon(dot)windsor(at)cornfield(dot)me(dot)uk

“There is nothing in the world that some man cannot make a little worse and sell a little cheaper, and he who considers price only is that man's lawful prey.”