PostgreSQL: format interval as minutes

Question

When I subtract timestamps, the interval is in form DD:HH:MM:SS. How can I convert it all to minutes without extracting days and hours and multiplication/addition? I'm looking for a single function which I can substitute for date_part in this query so that it returns 65:

select date_part('minutes', '65 minutes'::interval);

Context: I need to know how many minutes have passed since given timestamp.

Answer 1

I don't actually think you can without doing a bunch of weirdness (like to_char) because minutes roll over at 59. Which is why you get:

postgres=# select date_part('minutes', '65 minutes'::interval);

date_part

     5

(1 row)

postgres=# select '65 minutes'::interval postgres-# ;

interval

01:05:00 (1 row)

Answer 2

SELECT EXTRACT(EPOCH FROM '2 months 3 days 12 hours 65 minutes'::INTERVAL)/60;

seems to work.

WARNING: "seems" is the key word.