[postgis-users] GeomUnion function

[Hubert Fröhlich]

Hi list,

I am working with Postgis 0.8.1 and GEOS 1.0.0, PostgreSQL 7.4.1 .

I want to use the GeomUnion(geometry1, geometry2) function.

When I apply GeomUnion on two arbitrary MULTIpolygons, I receive 
MULTIPOLYGONS or POLYGONS, depending on the relationship between the two 
geometries.

However, when I want to insert the result into a table, I have to decide 
upon using only one geometry type.

If the result is a MULTIPOLYGON and I insert a to a table with 
MULTIPOLYGONS, everything is fine.
If the result is a POLYGON and I insert a to a table with MULTIPOLYGONS,
I get a constraint violation like

ERROR:  new row for relation "lkrx" violates check constraint "$2"

What I need is a function converting Polygons into Multipolygons or a 
GeomUnion function forcing MULTI... results.

How can I do that?

Regards,

Hubert





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Dr.-Ing. Hubert Fröhlich			
Bezirksfinanzdirektion München 			
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