db-jdo-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Abe White <awh...@solarmetric.com>
Subject Re: Typos in spec dtd
Date Wed, 31 Aug 2005 01:45:58 GMT
> 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 

View raw message