The view 'public.export2' has no column suitable for use as a unique key.
Quantum GIS requires that the view has a column that can be used as a unique key. Such a column should be derived from a table column of type int4 and be a primary key, have a unique constraint on it, or be a PostgreSQL oid column. To improve performance the column should also be indexed.
The view you selected has the following columns, none of which satisfy the above conditions:
'date_inserted' derives from 'public.wikimapia.datestamp' and is not suitable (type is date) and does not have a suitable constraint)
'date_taken' derives from 'public.panoramio.upload_date' and is not suitable (type is date) and does not have a suitable constraint)
'description' derives from 'public.flickr.description' and is not suitable (type is text) and does not have a suitable constraint)
'geom' derives from 'public.flickr.point_geom' and is not suitable (type is geometry) and does not have a suitable constraint)
'id' derives from 'public.flickr.point_geom' and is not suitable (type is geometry) and does not have a suitable constraint)
'service' derives from 'public.flickr.point_geom' and is not suitable (type is geometry) and does not have a suitable constraint)
'title' derives from 'public.panoramio.photo_title' and is not suitable (type is text) and does not have a suitable constraint)
'url' derives from 'public.flickr.photo_url' and is not suitable (type is text) and does not have a suitable constraint)