The strategy "mixing table per class hierarchy with table per subclass" is a
special and specific feature of Hibernate and NHibernate.The implementation
is
<class>
<discriminator ..../>
<subclass>
<join>
</join>
</subclass>
<subclass>
<join>
</join>
</subclass>
</class>
Reference here:
http://nhforge.org/doc/nh/en/index.html#inheritance-tablepersubclass-discriminator
2009/2/20 Piotr Jakóbczyk <[email protected]>
>
> Thanks for quick response.
> Let my explain in details what kind of mappings I need.
>
> We have composed hierarchy of objects with common base abstract class
> - BusinessObject. Until now we have whole hierarchy mapped by <joined-
> subclass>. But becouse of performance reasons and specificity of
> realized queries we want to horizontally divide base table of our
> hierarchy into a few distinct tables: TABLE1, TABLE2, TABLE3.
>
> The idea is following:
> For every new distinct tables should be prepared new classes:
> Class1Marker, Class2Marker, Class3Marker derivated from BusinessObject
> class.
> Class1Marker, Class2Marker and Class3Marker classes are mapped by
> <union-subcless>.
>
> In this way, we will have SHALLOW hierarchy of object derivated from
> BusinessObject class (stored in several tables: TABLE1, TABLE2,
> TABLE3).
> This hierarchy is sufficient for most of required and frequently
> executed queries and will be used for read only.
>
> But any of Class1Marker, Class2Marker, Class3Marker classes does not
> represent concrete object.
> So we want to prepare additional distinct hierarhies beased of a
> tables TABLE1, TABLE2, TABLE3. For each table separated hierarchy may
> used different inheritance strategy (mixing table per class hierarchy
> with table per subclass). To do this we need to prepare another
> mappings for tables TABLE1, TABLE2, TABLE3 and classes Class1, Class2,
> Class3 (not marker).
>
> Everything works fine untill mappings of BusinessObject and
> Class1Marker, Class2Marker, Class3Marker classes are placed before
> other mapping for tables TABLE1, TABLE2, TABLE3.
>
>
> On 20 Lut, 14:55, Fabio Maulo <[email protected]> wrote:
> > You CAN'T use <union-subclass> mapping more than one class to the same
> > table.
> > If you want use only one table you must use <subclass> or a trick like
> thishttp://fabiomaulo.blogspot.com/2008/10/power-of-orm.html
> >
> > 2009/2/20 Piotr Jakóbczyk <[email protected]>
> >
> >
> >
> >
> >
> > > I know what union-subclass is and I read references about all
> > > inheritance strategy implemented by NH.
> > > In my example I used <union-subclass> (look at SubclassA entity
> > > mapping).
> > > But why, in my example, the changing of the order of mapping
> > > definitions provide different behevoiur of NH. The first order raises
> > > exception, but the second not.
> >
> > > On 20 Lut, 13:45, Fabio Maulo <[email protected]> wrote:
> > > > union-subclass is an advanced way provided by NH to implement the
> mapping
> > > > pattern : table-per-concrete-class
> > > > What you are looking for is the implementation of the pattern :
> > > > table-per-class-hierarchy
> > > > The tag for that is <subclass>; reference available herehttp://
> > > nhforge.org/doc/nh/en/index.html#mapping-declaration-subclass
> >
> > > > --
> > > > Fabio Maulo
> >
> > > --
> > > Piotr Jakóbczyk
> >
> > --
> > Fabio Maulo
>
> --
> Piotr Jakóbczyk
> >
>
--
Fabio Maulo
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