On Mon, 2013-07-08 at 10:19 +0200, Andreas Joseph Krogh wrote:
> Hi.
> 
> Both of these queries return TRUE because NULL means "unmounded":
> select daterange('2013-07-01' :: DATE, null, '[]') && daterange('2013-07-04' :: DATE, '2013-07-30' :: DATE, '[]');
> select daterange(null, '2013-08-11' :: DATE, '[]') && daterange('2013-07-04' :: DATE, '2013-07-30' :: DATE, '[]');
> What is the rational behind this behavior of NULL?

It's just a convenience that passing NULL to a constructor creates an
unbounded range. The alternatives of having extra constructors for
unbounded ranges were discussed, but seemed more awkward.

Note that ranges do not allow either bound to be NULL. That would create
a lot of semantic problems.

Does that answer your question?