Re: Postgresql likes Tuesday...

Hannu Krosing <hannu(at)tm(dot)ee> writes:
> On Tue, 2002-10-01 at 03:31, Tom Lane wrote:
>> I notice that 2001-12-31 is considered part of the first week of 2002,
>> which is also pretty surprising:

> There are at least 3 different ways to start week numbering:
> ...
> I suspect it depends on locale which should be used.

Perhaps. But I think there are two distinct issues here. One is
whether EXTRACT(week) is assigning reasonable week numbers to dates;
this depends on your convention for which day is the first of a week
as well as your convention for the first week of a year (both possibly
should depend on locale as Hannu suggests). The other issue is what
to_date(...,'WWYYYY') should do to produce a date representing a week
number. Shouldn't it always produce the first date of that week?
If not, what other conventions make sense?

regards, tom lane