Alexander Farber <alexander(dot)farber(at)gmail(dot)com> writes:
> sorry for the stupid question, but why has the week number changed
> from 44 to 45 this night?
WW is defined as starting the first week on the first day of the year.
2010 started on a Friday so the week number increments on Fridays.
There are some other format codes with different behavior ...
regards, tom lane