pá 26. 6. 2020 v 7:29 odesílatel Thomas Kellerer <sham...@gmx.net> napsal:
> I regularly see people suggesting to use > > extract(day from one_timestamp - other_timestamp) > > to calculate the difference between two timestamps in days. > > But I wonder if the "format" of the resulting interval is guaranteed to > only have days > (and not months or years) > > The following: > > timestamp '2020-06-26 17:00:00' - timestamp '2019-04-01 14:00:00' > > returns an interval like this: > > 0 years 0 mons 452 days 3 hours 0 mins 0.0 secs > > However, is there ever a chance that the expression will yield the > (equivalent) interval: > > 1 years 2 mons 25 days 3 hours 0 mins 0.0 secs > postgres=# select age(timestamp '2020-06-26 17:00:00',timestamp '2019-04-01 14:00:00'); ┌────────────────────────────────┐ │ age │ ╞════════════════════════════════╡ │ 1 year 2 mons 25 days 03:00:00 │ └────────────────────────────────┘ (1 row) > > e.g. as the age() function does. > > Is it safe to assume that "timestamp - timestamp" will never contain units > larger then days? > Now, this operator internally calls only interval_justify_hours functions. So if somebody doesn't change related code, you can expect so only days, hours field's are changed. Regards Pavel > > > Thomas > > > >
