In bug #12367
http://www.postgresql.org/message-id/20141229031218.8013.51171@wrigleys.postgresql.org
we see yet another iteration of somebody trying to combine to_char's
IYYY specifier with regular Gregorian MM/DD fields.
It occurs to me that this is largely our own fault, because the fine
manual just defines IYYY as "ISO year". I'm sure the typical newbie
thought process is "that sounds like a standard year, I'll use that".
There is a warning against combining IYYY with MM/DD, but it's buried
in trivia far down the page.
I did a bit of googling and came across
http://en.wikipedia.org/wiki/ISO_week_date
in which this construct is called an "ISO week-numbering year".
Not having a copy of ISO 8601, I'm not sure if that's the standard's
terminology; but ISTM that if we consistently referred to the Ixxx
format specifiers as "ISO week-numbering foo" then this type of error
might become a little less attractive.
Objections, better ideas?
regards, tom lane