[postgis-users] multipolygom

[Nicklas Avén]

Hallo Marcel

i have not been playing that much myself with geography type but since
you already have your data in srid 4326 I guess you could just do
something like:

ALTER TABLE zip_polygon add column geog geography;

UPDATE zip_polygon set geog=geom::geography;

create index idx_zpoly_geog
on zip_polygon
using gist(geog);

vacuum analyze zip_polygon;


Then you should have the geography version of your geometries in column
geog and it should be indexed and analyzed.

/Nicklas




On Tue, 2011-02-08 at 13:33 +0100, Marcel Kroschel wrote:
> Hi Nicklas,
> your example works - thank you.
> How can i store it in geograpgy type?
> thx
> Marcel
> 
> ----- Ursprüngliche Mail -----
> Von: "Nicklas Avén" <nicklas.aven at jordogskog.no>
> An: "PostGIS Users Discussion" <postgis-users at postgis.refractions.net>
> Gesendet: Dienstag, 8. Februar 2011 12:46:14
> Betreff: Re: [postgis-users] multipolygom
> 
> To get the distance in meters you can use the geography type instead.
> 
> something like:
> 
> SELECT *
>  FROM zip_polygon
>  WHERE ST_DWithin(geom::geography, ST_GeogFromText('4326;POINT(13.171982
> 52.52646)'), 2);
> 
> But to get it working fast you should store in geograpgy type and build
> your spatial index n that.
> 
> HTH
> 
> Nicklas
> 
> 
> 
> On Tue, 2011-02-08 at 12:29 +0100, Marcel Kroschel wrote:
> > hi @all.
> > Hope someone can help me ;)
> > I uses postgis 1.5.2., create a table with with multipolygon and lng/lat coordinates called zip_polygon
> > 
> > SELECT AddGeometryColumn ( 'zip_polygon', 'geom', 4326, 'MULTIPOLYGON', 2 );
> > 
> > When ich want all polygons in distance i use this query:
> > SELECT *
> > FROM zip_polygon
> > WHERE ST_DWithin(geom, ST_GeomFromText('POINT(13.171982 52.52646)', 4326), 0.02);
> > 
> > But the manual say, that the last entry is the distance in meter. When i replace the 0.02 to the value 1, then i get the whole list.
> > 
> > example of geom - entry (SELECT (ST_AsText(geom)) from zip_polygon zp):
> > "MULTIPOLYGON(((13.69375 50.82966,13.69252 50.83034,13.68925 50.83206,13.68766 50.83374,13.68639 50.83576,13.68399 50.83782,13.68235 50.8386,13.72514 50.81991)))"
> > 
> > greeting
> > Marcel
> > 
> > 
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> > 
> 
> 
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