Обсуждение: date - date returns integer?

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Should date - date return type integer, not interval?

/* ahammond@test:5432/test =# */ SELECT ('2005-03-04'::timestamp -
'2005-01-01'::date)::interval;
~ interval
- ----------
~ 62 days
(1 row)

/* ahammond@test:5432/test =# */ SELECT ('2005-03-04'::date -
'2005-01-01'::date)::interval;
ERROR:  cannot cast type integer to interval

- --
Andrew Hammond    416-673-4138    ahammond@ca.afilias.info
Database Administrator, Afilias Canada Corp.
CB83 2838 4B67 D40F D086 3568 81FC E7E5 27AF 4A9A
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On Fri, Mar 04, 2005 at 15:59:02 -0500, Andrew Hammond <ahammond@ca.afilias.info> wrote:
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> Should date - date return type integer, not interval?

Yes. This is in the documentation.

Andrew Hammond <ahammond@ca.afilias.info> writes:
> Should date - date return type integer, not interval?

If we made it return interval then there would be all sorts of timezone
dependencies introduced (think about DST crossings) ... which is
generally something you don't want to think about when doing date
arithmetic.  I think the definitions of these operators are fine.
        regards, tom lane