Thread: BUG #13848: 2016 Week Number Error
The following bug has been logged on the website: Bug reference: 13848 Logged by: Max Kulinich Email address: maxk@yelp.com PostgreSQL version: 9.4.5 Operating system: OSX Description: SELECT EXTRACT(Week FROM current_date) = 1 instead of 2 Week numbers are all off
On Tue, Jan 5, 2016 at 1:32 PM, <maxk@yelp.com> wrote: > The following bug has been logged on the website: > > Bug reference: 13848 > Logged by: Max Kulinich > Email address: maxk@yelp.com > PostgreSQL version: 9.4.5 > Operating system: OSX > Description: > > SELECT EXTRACT(Week FROM current_date) =3D 1 instead of 2 Week numbers ar= e > all > off > =E2=80=8BThis looks correct to me. http://www.postgresql.org/docs/9.5/interactive/functions-datetime.html#FUNC= TIONS-DATETIME-EXTRACT <quote> week The number of the ISO 8601 week-numbering week of the year. By definition, ISO weeks start on Mondays and the first week of a year contains January 4 of that year. In other words, the first Thursday of a year is in week 1 of that year. In the ISO week-numbering system, it is possible for early-January dates to be part of the 52nd or 53rd week of the previous year, and for late-December dates to be part of the first week of the next year. For example, 2005-01-01 is part of the 53rd week of year 2004, and 2006-01-01 i= s part of the 52nd week of year 2005, while 2012-12-31 is part of the first week of 2013. It's recommended to use the isoyear field together with week = to get consistent results. </quote> =E2=80=8BJan 1, 2016 was on =E2=80=8Ba Friday. The first Thursday of 2016 i= s 7 Jan. ISO calendars start on a Monday (unlike US calendars which start on a Sunday), so the ISO first week of 2016 is Jan 4, 2016 to Jan 10, 2016. --=20 Werner Heisenberg is driving down the autobahn. A police officer pulls him over. The officer says, "Excuse me, sir, do you know how fast you were going?" "No," replies Dr. Heisenberg, "but I know where I am." Computer Science is the only discipline in which we view adding a new wing to a building as being maintenance -- Jim Horning Schrodinger's backup: The condition of any backup is unknown until a restore is attempted. He's about as useful as a wax frying pan. Maranatha! <>< John McKown
On Tue, Jan 5, 2016 at 8:32 PM, <maxk@yelp.com> wrote: > The following bug has been logged on the website: > > Bug reference: 13848 > Logged by: Max Kulinich > Email address: maxk@yelp.com > PostgreSQL version: 9.4.5 > Operating system: OSX > Description: > > SELECT EXTRACT(Week FROM current_date) = 1 instead of 2 Week numbers are all > off If you did on Jan 5, it was correct. RTFM, from http://www.postgresql.org/docs/9.4/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT >>> week The number of the ISO 8601 week-numbering week of the year. By definition, ISO weeks start on Mondays and the first week of a year contains January 4 of that year. In other words, the first Thursday of a year is in week 1 of that year. In the ISO week-numbering system, it is possible for early-January dates to be part of the 52nd or 53rd week of the previous year, and for late-December dates to be part of the first week of the next year. For example, 2005-01-01 is part of the 53rd week of year 2004, and 2006-01-01 is part of the 52nd week of year 2005, while 2012-12-31 is part of the first week of 2013. It's recommended to use the isoyear field together with week to get consistent results. <<< January 4 was a monday, so week from 4 to 10 is 1. 1,2,3 of jan belong to week 53 of 2015 ( as even my dead-tree calendar shows ). => select extract(week from '2016-01-05'::date), extract(isoyear from '2016-01-05'::date); date_part | date_part -----------+----------- 1 | 2016 (1 row) => select extract(week from '2016-01-01'::date), extract(isoyear from '2016-01-01'::date); date_part | date_part -----------+----------- 53 | 2015 (1 row) => select extract(week from '2016-01-03'::date), extract(isoyear from '2016-01-03'::date); date_part | date_part -----------+----------- 53 | 2015 (1 row) => select extract(week from '2016-01-04'::date), extract(isoyear from '2016-01-04'::date); date_part | date_part -----------+----------- 1 | 2016 (1 row) Francisco Olarte.
maxk@yelp.com writes:
> SELECT EXTRACT(Week FROM current_date) = 1 instead of 2 Week numbers are all
> off
Not a bug. See the manual's definition of this field:
: The number of the ISO 8601 week-numbering week of the year. By
: definition, ISO weeks start on Mondays and the first week of a year
: contains January 4 of that year. In other words, the first Thursday of a
: year is in week 1 of that year.
regards, tom lane