Re: special integrity constraints

On Mon, Mar 22, 2004 at 14:10:42 +0100, Erik Thiele <erik@thiele-hydraulik.de> wrote:
> 
> it means (((count_rows(a)+count_rows(b)) modulo 2) == 0)

OK, that means my FK suggestion won't help. The other suggestion about
putting triggers on "a" and "b" to update a count in another table
that has a deferred check constraint on it may be your best bet.
This will be a source of contention, but that may or may not be all
that important depending on how often you are updating "a" and "b".