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From Thomas Dudziak <to...@first.fhg.de>
Subject Re: mixed mapping (1 table/1 class, 1 table/many)
Date Sat, 10 Jul 2004 10:25:45 GMT
Jakob Braeuchi wrote:

> hi all,
> 
> i'm currently working on support for mixed-mapping within a class 
> hierarchy.
> it's now possible to use 1 table/1 class and 1 table/many classes 
> (ojbConcreteClass) within the class hierarchy.
> the implementation is still based on adding additional criteria for 
> ojbConcreteClass to a copy of the query, but it's done dynamically when 
> processing all concrete extents.
> 
> i was also thinking of a query wrapper to transport ojbConcreteClass so 
> i do not have to copy the query and manipulation the criteria. this 
> solution would require some refactoring of the jdbc/sql part of ojb.

There are at least two problems with ojbConcreteClass and queries that I 
know of, perhaps you could have a look at them while you're at it ?

* Queries seem to not respect inheritance hierarchies that use the 
multiple-joined-tables strategy (which requires that no extent-class is 
used, and ojbConcreteClass is useless in this scenario), see this thread:

http://nagoya.apache.org/eyebrowse/BrowseList?listName=ojb-user@db.apache.org&by=thread&from=819109

* If you remember we had a discussion last month with Andrew Clute about 
the possibility to specify something like ojbConcreteClass on the other 
end of a reference/collection:

http://nagoya.apache.org/eyebrowse/BrowseList?listName=ojb-user@db.apache.org&by=thread&from=766552


Also it would be nice to make the name of the concrete-class field 
configurable.

I don't know how much additional work that would mean, though ;-)

Tom

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