public function increase( $count = 1 )
    {
        // The attribute is naively incremented, despite possible updates in the DB.
        $this->setAttribute( 'count', $this->attribute( 'count' ) + $count );
        // However, we are not using ->store() here so that we atomatically update
        // the value of the counter in case it has been updated in parallel.
        eZDB::instance()->query(
            "UPDATE ezview_counter " .
            "SET count = count + " . (int)$count . " " .
            "WHERE node_id=" . $this->attribute( "node_id" )
        );
    }