Postgres: Генерация случайной строки

CREATE OR REPLACE FUNCTION fx_rndstr(n integer)
  RETURNS character varying AS
$BODY$
DECLARE
    count integer;
    retValue varchar;
BEGIN
    retValue := '';
    FOR count IN 1..n LOOP
        retValue:=retValue || chr( (floor(random()*26+65))::integer );
    END LOOP;
    RETURN retValue;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE SECURITY DEFINER
COST 100;