Re: 8.3 vs HEAD difference in Interval output?

Tom Lane wrote:
> In the integer-timestamp world we know that the number is exact in
> microseconds. We clearly ought to be prepared to display up to six
> fractional digits, but suppressing trailing zeroes in that seems
> appropriate.

Great.

> We could try to do the same in the float case, but I'm a bit worried
> about finding ourselves showing "1234567.799999" where it should be
> "1234567.8".

If I understand the code right fsec should mostly be values
between -1 and 1 anyway, because even in the floating point
case seconds are carried in the tm->tm_sec part.
It looks to me that a double should be plenty to do
microseconds so long as we don't put big numbers into fsec.
printf("%.99f\n",59.111111111111111111);
59.11111111111111426907882 ...

Anyway - I'll try showing up-to-6-digits in both cases and
seeing if I can find a test case that breaks.

I guess this rounding trickiness with rounding explains some of
the bizarre code like this too:
#if 0
/* chop off trailing one to cope with interval rounding */
if (strcmp(str + len - 4, "0001") == 0)
{
len -= 4;
*(str + len) = '\0';
}
#endif