Re: BUG #16620: Autovacuum does not process certain databases after migration from postgresql 10

Max Vikharev <bm.kinder@gmail.com> writes:
> Problem gone after restarting the cluster.
> Autovacuum started to process relations in other databases.

Hmm, interesting.

> I dont know how to reproduce the issue, we will monitor it.
> If there any way to debug it when it occurs again - let me know.

Did you by any chance capture the contents of pg_database.datfrozenxid
and datminmxid and compare them to the pg_class.relfrozenxid and
relminmxid fields in the problematic databases?

It's not hard to imagine that if the pg_database fields somehow
didn't get updated correctly during pg_upgrade, that would prevent
autovacuum from processing some databases to prevent wraparound.
However, that doesn't explain failure to examine those databases
at all, so I'm a bit at a loss.

Another thing to check is whether the stats collector is working.
Specifically look at whether counts in pg_stat_all_tables are
incrementing in the problem databases.

My guess is that somehow pg_upgrade left something in a slightly
hosed state, and that restarting de-hosed it, so that you aren't
going to see this again ... at least not till your next upgrade.
But I don't know exactly what the something could be.

            regards, tom lane