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| Re: EMF Database Schema: Custom or Generic? [message #759006 is a reply to message #759003] |
Fri, 25 November 2011 14:53  |
 Martin Taal
Messages: 5468
Registered: July 2009 |
Senior Member |
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Hi Hauke,
Teneo supports what you ask, it is the Entity-Attribute-Value schema:
http://wiki.eclipse.org/Teneo/Hibernate/ModelRelational/Entity_Attribute_Value_Mapping
you can even combine EAV mapped eclasses with 'normally' mapped eclasses.
But eventhough Teneo supports this... (without knowing your specific case) in all it is much much easier to have a
classic database schema and allow database changes. My experience with database model changes is that it is no problem
to do these changes in the model:
- remove eclasses from the model (the table is just ignored)
- remove nullable/non-mandatory efeatures from the model (column is just ignored)
- add eclasses (new tables can be created by hibernate)
- add nullable/non-mandatory efeatures to existing eclasses
These changes do not require explicit data migration.
Another project which might be interesting is Texo, it is an EMF variant which generates code which works standard with
any ORM:
http://wiki.eclipse.org/Texo
gr. Martin
On 11/25/2011 03:42 PM, Hauke Fuhrmann wrote:
> Hi there,
>
> I want to learn about possibilities to persist EMF Model Instances in relational databases.
>
> I'm looking for a way that always keeps the same generic database schema no matter what EMF Metamodel I use. I want to
> avoid that I have to change DB schemas in a productive database during operation.
>
> Is there such EMF-DB mapping available (e.g. some abstraction on objects mapped to quite few DB tables like "Classes"
> and "Instances" or something like that)?
>
> I'm aware that such abstract mapping might be quite inperformant and that you could have problems when the EMF schema
> changes and you have to migrate old DB objects manually.
>
> However, is there any such approach? Do you have any pointers for me?
> Are there other generic approaches, like using NoSQL databases (e.g. MongoDB)?
>
>
> Cheers,
> Hauke
--
With Regards, Martin Taal
Springsite/Elver.org
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