bq. My new code returns 0.2 months for this, not zero
Can you clarify (the output below that was 2 mons, not 0.2) ?
Thanks
On Fri, Apr 2, 2021 at 4:58 PM Bruce Momjian <bruce@momjian.us> wrote:
On Fri, Apr 2, 2021 at 02:00:03PM -0700, John W Higgins wrote: > On Fri, Apr 2, 2021 at 11:05 AM Bruce Momjian <bruce@momjian.us> wrote: > While maybe there is an argument to fixing the negative/positive rounding issue > - there is no way this gets solved without breaking the current implementation > > select interval '0.3 years' + interval '0.4 years' - interval '0.7 years' + > interval '0.1 years' should not equal 0 but it certainly does.
My new code returns 0.2 months for this, not zero:
> Unless we take the concept of 0.3 years = 3 months and move to something along > the lines of > > 1 year = 360 days > 1 month = 30 days > > so therefore > > 0.3 years = 360 days * 0.3 = 108 days = 3 months 18 days > 0.4 years = 360 days * 0.4 = 144 days = 4 months 24 days > 0.7 years = 360 days * 0.7 = 252 days = 8 months 12 days > > Then, and only if we don't go to any more than tenths of a year, does the math > work. Probably this should resolve down to seconds and then work backwards - > but unless we're looking at breaking the entire way it currently resolves > things - I don't think this is of much value. > > Doing math on intervals is like doing math on rounded numbers - there is always > going to be a pile of issues because the level of precision just is not good > enough.
I think the big question is what units do people want with fractional values. I have posted a follow-up email that spills only for one unit, which I think is the best approach.
