Bill,
> The question is: how do I add the first group? The very first group
> is
> the root group, and doesn't have a parent.
>
> My choices seem to be to either:
>
> - create the table without the constraint, add a group that will be
> the
> parent of all "root" groups, then add the constraint. The problem
> with
> this solution seems to be that dump and restores will be
> problematic.
This is exactly what you do, and pg_dump puts the constraints at the
end of the file to allow this sort of data load.
> So, kind sirs/madams, what am I missing?
Well, you should pick up a copy of Joe Celko's "SQL For Smarties" (2nd
Ed.), which has 20 pages on tree structures that will save you a lot of
headaches.
-Josh
