[postgis-users] HELP - Geometrycollection - CREATE VIEW - Empty Table

[ofoerster at posteo.de]

Hello PostGIS Community,

I have a Problem. I have a table with a geometry collection (polygon and 
point).
QGIS can not read the geometry collection, so I want to create a view 
for the polygon type and the point type. My SQL function for the polygon 
type looks like this:

CREATE VIEW parcel_polygons AS (
     SELECT
     row_number() OVER(ORDER BY inspire_local DESC) AS OID
     , inspire_local
     , inspire_namespace
     , label
     , nationalcadref
     , areavalue
     , validfrom
     , beginlifespanversion
     , zoning
     , geom::geometry(Polygon, 25833)
     FROM cp_parcel_postgis
     WHERE GeometryType(geom) = 'GEOMETRYCOLLECTION(POLYGON)'
)

I do not get any errors and the view is created. Unfortunately, the view 
is empty.
What am I doing wrong?

Thanks for any help,
Oli