Re: Common Table Expressions (WITH RECURSIVE) patch

On Tue, 2008-09-09 at 09:47 -0400, Robert Haas wrote:
> > 3. "I think this is a "must fix" because of the point about volatile
> > functions --- changing it later will result in user-visible semantics
> > changes, so we have to get it right the first time."
> >
> > I don't entirely agree with #3. It is user-visible, but only in the
> > sense that someone is depending on undocumented multiple-evaluation
> > behavior.
>
> What makes you think it's going to be undocumented? Single versus
> multiple evaluation is a keep aspect of this feature and certainly
> needs to be documented one way or the other. I can't understand why
> we would introduce a standard syntax with non-standard behavior, but
> if we do, it certainly had better be mentioned in the documentation.
>

I meant that -- hypothetically if we did accept the feature as-is -- the
number of evaluations would be documented to be undefined, not N. That
would avoid the backwards-compatibility problem.

This one point is probably not worth discussing now, because argument
#1 and #2 stand on their own.

Regards,
Jeff Davis