Testcase derived:
$ sudo -u postgres psql -c 'CREATE DATABASE test;'
$ sudo -u postgres psql -d test -c 'CREATE PROCEDURE test() LANGUAGE plpgsql AS
$$ BEGIN ROLLBACK; END; $$;';
$ sudo -u postgres psql -c 'DROP DATABASE test;'
Good:
CREATE DATABASE
CREATE PROCEDURE
DROP DATABASE
Bad:
CREATE DATABASE
2021-08-16 16:04:30.556 GMT [23081] ERROR: could not load library
"/usr/lib/postgresql/12/lib/plpgsql.so": /usr/lib/postgresql/12/lib/plpgsql.so:
undefined symbol: EnsurePortalSnapshotExists
2021-08-16 16:04:30.556 GMT [23081] STATEMENT: CREATE PROCEDURE test()
LANGUAGE plpgsql AS $$ BEGIN ROLLBACK; END; $$;
ERROR: could not load library "/usr/lib/postgresql/12/lib/plpgsql.so":
/usr/lib/postgresql/12/lib/plpgsql.so: undefined symbol:
EnsurePortalSnapshotExists
DROP DATABASE
And I can switch in/out of the bad state by making the on-disk plpgsql.so to
mismatch the running one.
$ v=12.2-4; apt install postgresql-12=$v postgresql-client-12=$v libpq5=$v
$ v=12.8-0ubuntu0.20.04.1; apt install postgresql-12=$v postgresql-client-12=$v
libpq5=$v
I'll set this to confirmed and I'm happy that we know the root cause.
But there isn't much more we can do.
In qemu we have had a similar issue, the answer would be per-build
directories that have to stay after upgrade/remove and cleared on e.g.
reboot. This can get very messy and the underlying issue is true to each
and every program that we SRU.
I think no action has to be taken - if anything then I'd want to have
postgresql to keep the .so in memory - because even if I successfully load it
on the old version, post upgrade it will fail.
So it did not keep the .so loaded. That probably is due to spawned off worker
threads I guess but there might be an efficiency gain just by not-loading libs
every time (independent to being slightly safer on upgrades).
I'll ping a few pstgresq people on this what they think about it.
** Changed in: postgresql-12 (Ubuntu)
Status: New => Confirmed
** Changed in: postgresql-12 (Ubuntu)
Importance: Undecided => Wishlist
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https://bugs.launchpad.net/bugs/1939898
Title:
Unnatended postgresql-12 upgrade caused MAAS internal error
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