I'm (again) considering deprecating toplevel collections and subcollections
in Hibernate 2.0. I was never completely happy with this feature after I
implemented it, but it had taken so much effort to get it to work that I left it in.
The case against toplevel collections is:
* the relational model is broken - there is no foreign key constraint from
collection element row to the owning row
* subcollections complicate code in SessionImpl _significantly_
The case for keeping them is:
* they let you persist a Java "collection of collections"
* they let you have a single table / collection mapping that can be used by
different owning classes
* instances of a toplevel collection can be passed between different owners
(even between owners of a different class, potentially) without needing to
remove and recreate the collection rows
* they currently work and I havn't needed to touch the complicated code for
a long time now
So: Do people USE this feature?? Have people really actually found uses
for this stuff, or is it actually just making Hibernate harder to understand
for the first time? Even if it has been useful, is perhaps *still* undesirable,
because of concerns about data integrity? Perhaps we simply shouldn't
be encouraging this kind of relational model.....
I need advice on this.
Gavin
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