Re: [SQL] Interval subtracting

Mark Dilger <pgsql@markdilger.com> writes:
> Tom Lane wrote:
>> If so, one function or the other is cheating.

> That depends what you mean by cheating.  The justify_hours function
> looks to see what answer justify_days would give, but does not
> actually change the data.  I described this all earlier and I still
> don't see why there is anything wrong with it.

The problem is that you can't determine "what answer justify_days would
give" without using the assumption "1 month == 30 days", which is an
assumption that justify_hours must not depend on.
        regards, tom lane