mgr inż. Jacek Bzdak <jbzdak@gmail.com> writes:
> I guess (I have no idea really) that there is some bug in pg_stat_activity
> view, because if I use function pg_stat_get_activity(NULL::integer) I will
> get one connection.
If you look at the definition of the pg_stat_activity view, you'll see
it's just a join of pg_stat_get_activity's output against pg_database and
pg_authid. It sounds like you had a row that had failed to join against
pg_authid --- maybe you dropped a user that still had a running session?
regards, tom lane