On Thu, Jul 22, 2021 at 2:59 PM Zhihong Yu <zyu@yugabyte.com> wrote:
On Wed, Jul 21, 2021 at 6:43 PM Bruce Momjian <bruce@momjian.us> wrote:
On Wed, Jul 21, 2021 at 06:39:26PM -0700, Bryn Llewellyn wrote: > Your statement > > > “months-to-days conversion is almost always an approximation, while the > days to seconds conversion is almost always accurate.” > > > is misleading. Any conversion like these (and also the “spill up” conversions > that the justify_hours(), justify_days(), and justify_interval() built-in > functions bring) are semantically dangerous because of the different rules for > adding a pure months, a pure days, or a pure seconds interval to a timestamptz > value.
We are trying to get the most reasonable output for fractional values --- I stand by my statements.
> Unless you avoid mixed interval values, then it’s so hard (even though it is > possible) to predict the outcomes of interval arithmetic. Rather, all you get > is emergent behavior that I fail to see can be relied upon in deliberately > designed application code. Here’s a telling example:
The point is that we will get unusual values, so we should do the best we can.
