Postgres 16

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CREATE TABLE test(id, created_on, closed_on) AS (VALUES
(1, 1654850834025, 1687168395586)
);

SELECT 1

SELECT 
    (closed_on - created_on) * interval '1 millisecond' as interval1,
    justify_interval(32317561561 * interval '1 millisecond') as interval2,
    to_timestamp(closed_on / 1000)::timestamp - to_timestamp(created_on / 1000)::timestamp as interval3,
    to_timestamp(created_on / 1000)::timestamp as created_on,
    to_timestamp(closed_on / 1000)::timestamp as closed_on
FROM test

interval1
interval2
interval3
created_on
closed_on

8977:06:01.561
1 year 14 days 01:06:01.561
374 days 01:06:01
2022-06-10 08:47:14
2023-06-19 09:53:15

SELECT 1

SELECT age(to_timestamp(closed_on / 1000), to_timestamp(created_on / 1000))
FROM test

age

1 year 9 days 01:06:01

SELECT 1