On Thu, Jul 25, 2013 at 4:18 AM, Giuseppe Broccolo <
giuseppe(dot)broccolo(at)2ndquadrant(dot)it> wrote:
> (TG_OP = 'UPDATE' AND
> (NEW.b != OLD.b OR
> (NEW.b IS NULL AND OLD.b IS NOT NULL) OR
> (NEW.b IS NOT NULL AND OLD.b IS NULL)
> )
> ) THEN
>
Unrelated to the OP's question, the suggestion above could be more simply
rewritten as
TG_OP = 'UPDATE'
AND NEW.b IS DISTINCT FROM OLD.b