Re: [udig-devel] Spatial Queries using CQL in uDig

[Andrea Aime <aaime@xxxxxxxxxxx>]

Jody Garnett ha scritto:
> I had not thought of that; I always figured that the datastore should
> handle this part (especially if the actual units are provided). If
> people are keen we could review the postgis code and make a utility
> method for the various datastore implementations to call?

Very few data sources actually have the machinery to deal with
dwithin on geographic data.
PostGIS does only starting with version 1.5, Oracle does,
I guess probably DB2 does too, maybe SDE too.
That said, I have no idea if the SQL encoders actually pass
down the unit.

To support shapefiles we'd have to add code to make the in
memory dwithin take care of the math necessary to compute
point to line distances on an ellipsoid (the code I was
referring to before)

Cheers
Andrea


--
Andrea Aime
OpenGeo - http://opengeo.org
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