Question

Consider the following statement:

select interval '-1 hours'

I couldn’t figure out how to get the absolute value of an interval, i.e. to toggle or remove the sign if negative. The only thing that came to my mind is the following:

select abs(extract(epoch from interval '-1 hours'))

But I wonder if there is a more elegant way (a way that preserves the interval type)?

Answer 1

A CASE expression would look more self-explanatory. Example:

SELECT
    i,
    (CASE WHEN (i < INTERVAL '0') THEN (-i) ELSE i END) AS abs_i
FROM
    (VALUES
        (INTERVAL '-2 h'),
        (INTERVAL '2 m')
    ) AS foo (i)

which produces:

     i     |  abs_i
-----------+----------
 -02:00:00 | 02:00:00
 00:02:00  | 00:02:00