Is there a better way to retrieve a random row from an Oracle table?

Not so long ago I needed to fetch a random row from a table in an Oracle database. The most widespread solution that I've found was this:

SELECT * FROM
( SELECT * FROM tabela WHERE warunek
ORDER BY dbms_random.value )
WHERE rownum = 1​ 

However, this is very performance heavy for large tables, as it sorts the table in random order first, then grabs the first row.

Today, one of my collegues suggested a different way:

    SELECT * FROM (
    SELECT * FROM MAIN_PRODUCT
    WHERE ROWNUM <= CAST((SELECT COUNT(*) FROM MAIN_PRODUCT)*dbms_random.value AS INTEGER)
    ORDER BY ROWNUM DESC

) WHERE ROWNUM = 1; 

It works way faster and seems to return random values, but does it really? Could someone give an insight into whether it is really random and behaves the way as expected? I'm really curious why I haven't found this approach anywhere else while looking, and if it is indeed random and way better performance wise, why isn't it more widespread?