Stephan,
> AFAIK we don't actually have statement triggers right now, anyway,
> but...
> Actually, I guess an after trigger that just checked the new values
> would
> work as well, right? See if there exists more than one row with the
> new
> key value. The after trigger should fire after all the changes are
> done
> and in the worst case you could use constraint triggers and
> deferment.
> The hard part about this really is making it work with concurrent
> modifications, and if you're willing to forgo that, it shouldn't be
> too
> bad.
Thanks. I'll give your solution a try and see what the performance hit
is.
Is the Unique Constraint issue on the To-Do list?
Chris: The "holding value" solution won't work for me. I'm usually
changing dozens of values at a time, and they need to stay in the same
sequence while blocks of them move on the scale.
FYI, I'm implementing Joe Celko's "Linear Nested Set Model" of tree
structures.
-Josh Berkus
