[postgis-devel] WKT Raster: Back from RT_ to ST_

Havard Tveite havard.tveite at umb.no
Mon Apr 6 01:59:14 PDT 2009

I agree with strk, reserve the ST prefix for things that complies
with the SQL/MM Spatial standard.  The fact that the standard
currently is not followed in all details by all (commercial)
spatial DBMS products, and that the standard itself might not be
specific enough on some of the details does not justify that
PostGIS shall add to the confusion!
Instead of "dismissing" the the standard we should help improve
it - we need the standard.
In my opinion, a good open source spatial database management
system should take standards compliance very seriously.
Standards compliance has been one of the major "selling points"
of PostGIS, and standards are very important for the success of
open source products such as PostGIS!

We should use other prefixes than ST or no prefixes at all for
PostGIS specific things.

Håvard Tveite

Paragon Corporation wrote:
> Strk,
> Your code wouldn't just work anyway.  There is enough variant between the
> IBM, MS, Oracle, PostGIS, ArcSDE (dear I mention MySQL here) versions that
> the "just work" idea doesn't "just work".  At best you are talking about
> portability of knowledge.  It would just "sort of work".  
> For example MS uses camel case so its STIntersects not ST_Intersects.
> Oracle based on my understanding if you use ST_GeomFromText you get a
> generic geometry object, but if you use ST_PolygonFromText you get a
> qualified Polygon object with completely different structure. Then Oracle
> has this whole ordinate array thing going on. I think IBM comes closest to
> being cross compatible with PostGIS but they allow mixed SRIDs I think and
> silently convert. Oracle ST_Distance takes unit type as an arg. So that's
> why I'm not too too bothered that we use ST_ a little more than we should.
> The reason I like the overloading idea for RASTER is that if you had written
> code to work with PostGIS geometries and later decided you want it to work
> with RASTER, I think its an easier exercise if RASTER uses the same names.
> Otherwise you'd have to macro replace the code everywhere.  You'd probably
> still need to test and depending on the language rewrite since the outputs
> are different, but my feeling is that it's a bit of an easier task if the
> names are the same.
> Thanks,
> Regina
> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net
> [mailto:postgis-devel-bounces at postgis.refractions.net] On Behalf Of strk
> Sent: Friday, April 03, 2009 4:39 AM
> To: PostGIS Development Discussion
> Subject: Re: [postgis-devel] WKT Raster: Back from RT_ to ST_
> On Thu, Apr 02, 2009 at 08:26:38PM -0400, Paragon Corporation wrote:
>> Yap ST_ thingy should have been left for only ISO stuff.  Right now I 
>> feel sort of torn since the damage has already been done; seems like a 
>> lot of effort to correct the wrong.  Maybe we can revisit in 2.0.
>> I do like the idea of overloading ST for raster though, but I think 
>> Paul was dead set against the idea because it would break OGC
> compatibility.
> Actually, I think anyone using postgis-specific things should use the
> version with no ST_ prefix. When you use ST_ it's because you're hoping your
> code will "just work" with any ISO-compliant thingy.
> If you're using rasters, and they are not ISO-standard, you should use
> Intersect() for both rasters and vectors. You know you're talking to postgis
> and not a generic ISO standard SF dbms.
> --strk; 
>  Free GIS & Flash consultant/developer      ()  ASCII Ribbon Campaign
>  http://foo.keybit.net/~strk/services.html  /\  Keep it simple! 
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Håvard Tveite
Department of Mathematical Sciences and Technology, UMB
Drøbakveien 31, POBox 5003, N-1432 Ås, NORWAY
Phone: +47 64965483 Fax: +47 64965401 http://www.umb.no/imt/

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