"Michael J. Baars" <mjbaars1977(dot)pgsql-hackers(at)cyberfiber(dot)eu> writes:
> So how do you compute the number of seconds in 8 years?
IMO, that's a meaningless computation, because the answer is not fixed.
Before you claim otherwise, think about the every-four-hundred-years
leap year exception in the Gregorian rules. Besides, what if the
question is "how many seconds in 7 years"? Then it definitely varies
depending on the number of leap days included.
What does make sense is timestamp subtraction, where the actual
endpoints of the interval are known.
regards, tom lane