Re: Incomprehensible behaviour of a foreign key.

"Nigel J. Andrews" <nandrews@investsystems.co.uk> writes:
> **** Attempt the delete ...
> **** ...and watch the empty table from the start cause a ref. int. failure!

Bizarre.  If the database is not too huge, I would ask you to please
make a tarball backup of the whole $PGDATA directory (while the
postmaster is stopped of course) before you go any further.  That way
we can get back to this state if needed for bug investigation.

With backup in hand, please try "VACUUM FULL VERBOSE site_membership"
and see what it has to say about rows in site_membership.  If it shows
that any were deleted, is the problem fixed?

            regards, tom lane