Re: Dates BC.

Kurt Roeckx wrote:
> I find this a little strange:
>
> select date_part('year', '0002-01-01 BC'::date);
> date_part
> -----------
> -1
>
> It seems 1 BC and 0 are the same year.
>
> In backend/utils/adt/formatting.c:
>
> if (tmfc.bc)
> {
> if (tm->tm_year > 0)
> tm->tm_year = -(tm->tm_year - 1);
>
> It this normal or a bug?

Uh, well, yea, there was no year 0. However, it seems we should return
the proper year. My guess is that missing year 0 is the cause, and
there are certain reasons year 2 BC should return -1. If you are
subtracting dates, like 32AD - 4BC, you get 35, which is the proper
number of years spanned.

I am not sure what is the proper answer. I thought date_part just
grabbed "parts of the date" like it says, but obviously not, and there
are some good reasons for it, I guess.

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