"Benjamin Krajmalnik" <kraj@illumen.com> writes:
> This happened again on another server with these same settings.
> I did not see any long running transaction, and the autovacuum launch
> process was running.
Hmm ... could you strace the launcher for a couple of minutes to see
whether it's doing anything?
Also, I've forgotten exactly which PG version you're running?
regards, tom lane
