'initialize the self.__tablecolumns dict'

def __load_column_info(self, table):

    try:
        tcolpickles = getattr(self.db, 'get_bytes', self.db.get)(_columns_key(table))
    except db.DBNotFoundError:
        raise TableDBError, ('unknown    table:    %r' % (table,))
    if (not tcolpickles):
        raise TableDBError, ('unknown    table:    %r' % (table,))
    self.__tablecolumns[table] = pickle.loads(tcolpickles)
