FW: [postgis-users] FW: [Psycopg] RELEASE: GeoTypes-0.2.0a1
nhv at cape.com
Thu Sep 25 03:26:00 PDT 2003
I have been forwarding your posts to the PostGIS list so that the
developers can participate. Perhaps you should just cross-post
there, so I don't have to do this manually :-)
> -----Original Message-----
> From: Richard Taylor [mailto:r.taylor at eris.qinetiq.com]
> Sent: Thursday, September 25, 2003 3:35 AM
> To: nhv at cape.com; psycopg at lamu.initd.org
> Subject: Re: FW: [postgis-users] FW: [Psycopg] RELEASE: GeoTypes-0.2.0a1
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> On Thursday 25 September 2003 2:09 am, Norman Vine wrote:
> > >
> > > Yes - this is probably the best thing to do. The OGC function
> > > GetGeometryType() basically tells you what type the actual geometry is.
> > > So, a MULTIPOLYGON returns "MULTIPOLYGON".
> > >
> > > Also, I suggest you plan for using WKB instead of WKT because its much
> > > more efficient (space wise), easier to parse, and you dont lose any
> > > precision in your coordinates.
> I will have to look into WKB before I go any further. I don't know what the
> issues are here. I guess I need to use a binary cursor in Psycopg (I have not
> used these before) and then work out how to parse the result in python. I
> will also have to read the WKB docs to understand it better.
> Would using the GetGeometryType() function require two trips to the database
> for each return? e.g.
> <list of geometry objects> = select geo_obj from geo_table;
> for each geometry_object
> geometry_sub_type = select GetGeometryType(geometry_object)
> I was trying to avoid this. It is possible to avoid it with the WKT format
> because the real sub type of the object is encoded in the format is this true
> of the WKB format? (I will read it anyway).
> - --
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