One thing i've always been curious about is why there are no separate cascades fro save and update. I've often thought such a feature very useful. Is this due to some technical concern? Will Hibenrate 3 allow cascading only on inserts and not on updates?

If there is no technical reason for it how simple would it be to modify hibernate to do this and where would I need to look?

thanks

The reason is functional, I don't think this would be very useful since it will only work for full insert (no update in the whole graph (ie no existing entity)
or for full update (no new entity in the whole graph).
It seems to me this is very uncommon

When you create an object with a collection for the first time it would be usefult to cascade the creation of the children. I often don't use the save-update cascade because an update on the parent forces updates on all the children whether they have been changed or not which is not good if there are a lot of children. But it does simplify the initial insert ( or am I doing something wrong?)

This is of course plain wrong.
hibernate does not update children unless they've been changed for real

emmanuel,
what's up guy?
teknokrat is right about update on children when a parent is detached and reattach using session.update(parent).

teknokrat,
You can avoid this by using select-for-update option in children mapping file. It isn't sure that it is more efficient but it is usefull to avoid trigger and version update.

yeah, its the detaching then attaching that triggers the update. I'll check out select for update though currently its not a major issue. Just curious, how will hibernate 3 will deal with different cascade semantics?

Hibernate3 has a number of "operations", each of which may have cascade independently enabled:

save-update
create
merge
delete
evict
lock
replicate
delete-orphan

(and maybe I should add cascade refresh)

you can combine cascade styles, eg:

cascade="create,merge,delete"
cascade="all,delete-orphan"
cascade="create,lock"