>> Because intervals (mathematical not SQL) can be open or closed at each >> end point we need to know what the next an previous value would be at >> the specified granularity. And while you can do some operations without >> knowing this, there are many you can't. For instance you could not tell >> whether two [] or () ranges were adjacent, or be able to coalesce an >> array of ranges. > > This statement seems to me to demonstrate that you don't actually > understand the concept of open and closed ranges. It has nothing > whatsoever to do with assuming that the data type is discrete; > these concepts are perfectly well defined for the reals, for example. > What it is about is whether the inclusion conditions are "< bound" > or "<= bound".
IMHO the first question is whether, for integers, [1,2] UNION [3,5] should be equal to [1,5]. In math this is certainly true, and defining 'next' seems like a reasonable way to establish this in postgres. The next question is whether, for floats, [1,3-FLT_EPSILON] UNION [3,5] should be [1,5]. And the next question is whether, for numeric(6,2), [1,2.99] UNION [3,5] should be [1,5]. FWIW, I would answer yes, no, yes to those three questions. -Nathan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers