On Jan 9, 2008 9:29 PM, Brendan Jurd <direvus@gmail.com> wrote:
> Sorry, a correction. The issue of years vs. days isn't ignored. A
> year is just 12 months, which yields 12 * 30 = 360 days, which is
> actually a pretty significant error (1.4% on average).
YEAR TO MONTH and DAY TO {HOUR,MINUTE,SECOND} intervals should not
combine. PostgreSQL correctly doesn't allow {YEAR,MONTH} TO
{DAY,HOUR,MINUTE,SECOND} intervals, and it shouldn't allow operating
on invalid intervals combinations either. One mistake that PG does
make is that it allows a "FULL RANGE" interval. This weirdness is
essentially a YEAR TO SECOND interval that isn't allowed when
explicitly requested.
wt-time=> select INTERVAL '1 year 1 month 1 day 1:1:1'; interval
-----------------------------1 year 1 mon 1 day 01:01:01
(1 row)
wt-time=> select INTERVAL '1 year 1 month 1 day 1:1:1' YEAR TO SECOND;
ERROR: syntax error at or near "SECOND"
LINE 1: select INTERVAL '1 year 1 month 1 day 1:1:1' YEAR TO SECOND;
^
This is inconsistent. I would like to ultimately not allow operations
on interval combinations that are not allowed by the SQL standard.
wt