Re: operator exclusion constraints

On Mon, 2009-11-02 at 18:28 +0000, Simon Riggs wrote:
> > I like the "NOT" here because "CHECK NOT =" seems to convey pretty
> > clearly what it is you are checking for.  Because NOT is reserved and
> > can't appear as a connective, I think that this approach might allow
> > a non-reserved leading word, thus possibly the second variant would
> > work without reserving CONSTRAIN.  I have not tested whether bison
> > agrees with me though ;-).  In any case I think "CHECK NOT =" reads
> > pretty well, and don't feel a strong urge to use some other word there.
> 

Peter, do any of these ideas work for you? It looks like this opens the
door to using a word other than CHECK. CONSTRAIN NOT is a little
awkward, is there another word that might work better?

I'm not excited about using NOT, because I think it has a hint of a
double-negative when combined with EXCLUSION. The original idea was to
specify the way to find tuples mutually exclusive with the new tuple;
and NOT makes that a little less clear, in my opinion. But I'm fine with
it if that's what everyone else thinks is best.

Regards,
	Jeff Davis