I wrote:
> Attached is a proposed patch against HEAD that fixes this by supporting
> default arguments properly for window functions. In passing, it also
> allows named-argument notation in window function calls, since that's
> free once the other thing works (because the same subroutine fixes up
> both things).
Hm, well, almost free --- turns out ruleutils.c was assuming WindowFuncs
couldn't contain named arguments. Updated patch attached.
regards, tom lane