Apache JDO Project - Re: Typos in spec dtd

Author

Re: Typos in spec dtd

Abe White

2005-08-30, 8:45 pm

> Could you please suggest what the semantics of mapping a single field
> to multiple columns means? Are you thinking of a multi-column foreign
> key usage for references (relationships) or do you see it applying to
> primitive values as well?

Certainly multiple columns are needed for compound foreign keys. But
being able to define multi-column mappings is also important to vendors
who allow their users to create custom mappings. For example, one of
Kodo's custom mapping samples maps a java.awt.Point to two columns --
one for the X coordinate and one for the Y coordinate. I don't think
the DTD should make expressing mappings like that unnecessarily
difficult.