On Jun 29, 2007, at 13:17 , John D. Burger wrote:
I can't anything in the docs that explain how intervals print out.
They seem to show like this:
> select now() - '1990-01-01';
?column?
-------------------------------
6388 days 13:06:26.3605600595
Without being anchored with a timestamp, we have no way to know how
long a given month is in the result, so it plays it safe by returning
everything in days.
or like this:
> select now() - current_date;
?column?
-----------------
14:06:46.119788
unless you use age(), which supposedly also returns an interval:
> select age(now(), '1990-01-01');
age
-----------------------------------------
17 years 5 mons 28 days 14:08:04.524803
Why do the first and third intervals print out differently?
The timestamp[tz]_age functions currently don't use the same
algorithm the timestamp_mi code does. This should probably be
reconciled in the future so results are consistent.
But age() is documented as simply producing an interval - where is
the magic that makes the first and third results above look different?
src/backend/utils/adt/timestamp.c
Ah, wait a minute - does this have to do with the varying number of
days in different months?
Yes.
Michael Glaesemann
grzm seespotcode net
