Re: Range types

Jeff Davis <pgsql@j-davis.com> writes:
> I think "need" and "flailing" are both a little too strong here. The
> biggest use case will almost certainly be ranges of timestamps, and most
> of those people will have no use for flag bits (or if they do, it might
> not be worth an 8-byte-per-value overhead).

When the alternatives are a crippled implementation that might not do
what I want at all, or a full-featured implementation that takes another
8 bytes per value, I'll take the second.  The 8 bytes don't matter if it
doesn't solve my problem.

> I would prefer to avoid allowing NULL range boundaries for the following
> reasons:
>   * it reminds me of MySQL dates with zeros in them

If we use that notation to represent an open-ended interval, it seems
perfectly reasonable to me.  And it doesn't require any assumptions
about whether the underlying type has an infinity.

I think it's a seriously bad idea to tell people that they should depend
on min or max values of a datatype to substitute for the lack of
open-ended intervals.  That sort of technique creates unnecessary
implementation dependencies, and magic numbers (especially ones with a
dozen or two digits in them) are bad things for readability in any case.

To take just one example that's pretty near at hand: if type date had
had an exact published max value that applications were hard-wiring into
their code, we'd not have been able to change it to add 'infinity' as a
special value.
        regards, tom lane