We had lots of design discussions lately. I hope we have the time to
implement even half of it :-).
Anyway, here is another one...
Working on the plan of TopLink -> Cayenne conversion I noticed that I will
need inheritance support in the mapping. Out of all types of inheritance
that are used in O/R design (vertical, horizontal, single table), I am
targeting "single table" for now.
I created a "pending" subfolder in "xdocs" as a place for design documents
that might eventually become a part of official documentation. There is a
file there called inheritance.xml with a description of how the mapping will
be done from the CayenneModeler perspective. Basically it will involve an
extra "Inheritance" tab for ObjEntity.
GUI is closer to TopLink rather than EOModeler, in that you can't select an
arbitrary qualifier for each of the subclass entities, but rather have a
designated "class indicator" column. This is to make the whole thing more
deterministic and avoid conflicting qualifiers (so that rows in the database
never resolve to more than one entity). Internally we may still use
Expression for this.
Comments?
Andrus
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