BUG #4372: TO_DATE with ISO week and day

Kees Westerlaken wrote:

The following bug has been logged online:

Bug reference: 4372
Logged by: Kees Westerlaken
Email address: kees.westerlaken@valuecare.nl
PostgreSQL version: 8.3.3
Operating system: Windows
Description: TO_DATE with ISO week and day
Details:

The TO_DATE conversion with ISO week (IW) and ISO day (ID) format accepts
invalid values and sometimes returns wrong result.

select to_date('2008-31-4','IYYY-IW-ID')
results in "2008-07-31", which is correct

The valid values for IW are 1-7, however:

I think you mean "valid values for ID".

select to_date('2008-31-8','IYYY-IW-ID')
results in "2008-08-04" of which you could argue if it is correct.

It is true we don't error out as often as Oracle for to_date(). We have
a TODO item for this:

Fix to_date()-related functions to consistently issue errors

* Invalid to_date patterns (was: [PATCHES] [GENERAL] ISO week dates)

However:
select to_date('2008-31-10','IYYY-IW-ID')
results in "2008-07-28", which is not correct

Well, as you said ID=10 isn't a valid value, so the code defaults to
Monday, but it seems it goes to the next week until Tuesday, then wraps
back, which is odd.

And even worse: if you use the IW and ID format in an older version it
works, but the result is wrong.
select to_date('2008-31-4','IYYY-IW-ID')
in version 8.2.6 results in "2004-07-26", which is wrong.

Yes, we have fixed some of this in 8.3.

I have added your report to the existing TODO item.

--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +