On Mon, 10 Nov 2014 14:14:15 +0100 Francisco Olarte <folarte@xxxxxxxxxxxxxx> wrote: > On Mon, Nov 10, 2014 at 10:07 AM, Ilya Ashchepkov <koctep@xxxxxxxxx> > wrote: > > > Is this correct? > > $ select > > justify_interval(t-f-i) > > ,t-f-i > > from > > ( > > select > > timestamp '2014-1-1' as f, > > timestamp '2015-1-1' as t, > > interval '06:49:00' as i > > ) S; > > > > justify_interval | ?column? > > ------------------------+-------------------- > > 1 year 4 days 17:11:00 | 365 days -06:49:00 > > > > Why do we have 360 days in a year? > > > > Seems to be, the docs says: > > justify_days(interval) interval Adjust interval so 30-day time > periods are represented as months justify_days(interval '35 days') 1 > mon 5 days justify_hours(interval) interval Adjust interval so > 24-hour time periods are represented as days justify_hours(interval > '27 hours') 1 day 03:00:00 justify_interval(interval) interval Adjust > interval using justify_days and justify_hours, with additional sign > adjustments justify_interval(interval '1 mon -1 hour') 29 days > 23:00:00 And, IIRC, an interval stores 3 parts, months, days and > secods. The 365 days are justified to 12 months 5 days by justify > days, then the 5 days - 6:49:0 are justified to 4 days 17:11:00 and > then the 12 months are printed as 1 year ( because months are printed > as MM/12 years, MM%12 months ). > > What I'm not sure is why the right column is stated as 365 days minus > six hours and change instead of 1 year minus six hours, maybe testing > the parts in sequence may shed light on it, but I wouldn't rely on > justify_xxx for any precise thing on big intervals given it's > definition ( unless you are working only with intervals and using 30 > days months, 24 hour days exclusively ). > > Francisco Olarte. > Thanks. I thought about justify_interval as function that formats interval to human readable string. Justify_hours result is more obvious. I will use it. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
