"David M. Kaplan" <dmkaplan(at)ucdavis(dot)edu> writes:
> I have found that !~ and !~* do not match the null string even when one
> would expect them to.
NULL strings won't match anything. I can't tell whether your row 3 is
an empty string or a NULL --- but if it's a NULL, this behavior is
not a bug. Try "s IS NULL" if you want to find NULLs.
regards, tom lane