如何将一个函数中的多个值选择到单独的列中?

SELECT
    *
FROM (
    SELECT 
        getlatlng("geom")
    FROM
        mytable
) AS subquery;

它回来了

(-121.9,36.4)
(-117.1,32.9)
(-121.9,36.5)
(-71.2,42.6)

我想写信

SELECT
    subquery.lat, subquery.lon 
FROM (
    SELECT 
        getlatlng("mygeom")
    FROM
        mytable
) AS subquery;

lat  | lon
-------------
36.4 | -121.9
32.9 | -117.1
36.5 | -121.9
42.6 | -71.2

下面是函数的相关位。

CREATE OR REPLACE FUNCTION getlatlng(geom geometry, OUT longitude text, OUT latitude text)
 RETURNS record
 LANGUAGE sql
 IMMUTABLE
AS $function$
SELECT ...;
$function$