"" <dueyduey@freemail.hu> writes:
> I am experiencing a very interesting, actually very frightening thing: I
> have a foreign key constraint along with rows violating it.
You have not provided enough information to let anyone reproduce or
debug the problem...
FWIW, we recently found a problem in VACUUM FULL that could result in
symptoms a bit similar to this --- do you routinely do VACUUM FULL while
the database is active?
regards, tom lane