[postgis-devel] Typmod Again

[Paul Ramsey]

FYI, I'm implementing this stuff within the context of GEOGRAPHY,
which allows us to sort of play with these ideas before rolling them
onto GEOMETRY in a breaking way. I do think that trying to hew closer
to the standards base for GEOMETRY when we do the 2.0 release would be
a good idea, try to put all the breaking changes we can think of into
one release.

P.

On Wed, Jul 22, 2009 at 2:30 PM, Paragon Corporation<lr at pcorp.us> wrote:
> No we don't
>
> POINTZ, POLYGONZ POLYGONZM, POINTZM  ->  just POINT, POLYGON  -- so we have
> POINT(1 2 3), POINT(1 2 3 4)
>
> Technically I believe we are in violation of the standards here.  So Paul's
> proposal -- while a breaking change would be more compliant.
>
> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net
> [mailto:postgis-devel-bounces at postgis.refractions.net] On Behalf Of Chris
> Hodgson
> Sent: Wednesday, July 22, 2009 5:25 PM
> To: PostGIS Development Discussion
> Subject: Re: [postgis-devel] Typmod Again
>
> According to the 1.4 manual, postgis has the following type options:
>
> The type of the spatial object. To restrict the spatial column to a single
> type, use one of: POINT, LINESTRING, POLYGON, MULTIPOINT, MULTILINESTRING,
> MULTIPOLYGON, GEOMETRYCOLLECTION or corresponding XYM versions POINTM,
> LINESTRINGM, POLYGONM, MULTIPOINTM, MULTILINESTRINGM, MULTIPOLYGONM,
> GEOMETRYCOLLECTIONM. For heterogeneous (mixed-type) collections, you can use
> "GEOMETRY" as the type.
>
> I don't see any Z options, let alone GEOMETRYZ/M. Do we really have
> different types for each possible type and 2/3/4-d combination?
>
> Chris
>
> Paul Ramsey wrote:
>> OK, working into the typmod implementation, I found this interesting
> quirk.
>> Before, I was talking about
>>
>> geometry(srid, type, dims)
>>
>> But, in fact, dims is implicit in type, and you probably want that.
>> IE, 'POINTZM' (as defined in Table 4 of SFSQL 1.2.0) is a valid type,
>> and implies a dimensionality of four. We want our types to include
>> that information so we can distinguish between POINTM and POINTZ,
>> otherwise, we could define geometry(4326, POINT, 3) and be able to
>> accept both POINTM and POINTZ.
>>
>> So that brings us down to just
>>
>> geometry(srid, type)
>>
>> Anything I'm missing?
>>
>> P
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>
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