order by of columns of inherited tables raises error

[Ferdinand]

trying to sort column name

ProgrammingError: column "name" does not exist
ZEILE 1: select dimu_portal.id from "dimu_portal" order by name DESC

class dimu_portal(osv.osv):
    _name = "dimu.portal"
    _table = "dimu_portal"
    _description = "Portal"
    _inherits = {'res.partner' : 'res_partner_id'}

I know it does not work - but IMHO it shouldn't raise an error either.
the error seems to do any harm...... except filling the log with red lines.