[postgis-devel] assumptions of &&& operator for missing dimensions

[Rémi Cura]

Clearly 2 for me !
Cheers,
Rémi-C

2015-02-24 17:05 GMT+01:00 Sandro Santilli <strk at keybit.net>:

> On Tue, Feb 24, 2015 at 04:26:02PM +0100, Even Rouault wrote:
> > Le mardi 24 février 2015 16:15:53, Sandro Santilli a écrit :
> > > On Tue, Feb 24, 2015 at 08:09:26AM -0500, Paul Ramsey wrote:
> > > > Well, the old semantic has been there since 2.0, which is a very long
> > > > time. A further question for it would be: what do the next functions
> do?
> > > > What does a distance calculation between a 2d and 3d object return?
> does
> > > > it also respect that semantic?
> > >
> > > I just checked and ST_3DDistance is instead still confusing:
> > > select ST_3DDistance('POINT Z (0 0 10)', 'POINT (0 0)'); -- 10
> > > I think it should be 0 instead.
> >
> > As an uninformed observer, 10 or an error because of heterogenous
> dimensions
> > would seem reasonable to me. But 0 would be very surprising !
>
> How about overlap then ? Should they overlap or not ?
>
>  'POINT Z (0 0 10)' &&& 'POINT (0 0)'
>
> That's were we started, original question was,
> which one do you prefer:
>
>     1. Missing dimension is unknown, return NULL
>     2. Missing dimension is infinite, overlaps everything
>     3. Missing dimension is empty, overlaps nothing
>     4. An impossible comparison was requested, raise exception
>
> On Thu, Feb 19, 2015 at 09:04:16AM -0800, Paul Ramsey wrote:
> > My preference was always to allow, for example,
> > a 2d query box to extract a 3d column of data from a volume
> > of points, and I would have implemented that way if I could.
> > Now, what i cannot tell you, is why I felt I couldn’t…
>
> --strk;
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