You are on the right track with your second idea.  Create a separate
kind for 'D'.  I am not familiar enough with the semantics of GAE-Java
to suggest a specific implementation.

In GAE-Python I would make the kind with A, B, C the parent of the
kind containing D, that would allow me to reconstruct D's datastore
key without running an expensive query.

Hopefully someone using GAE-Java could suggest a more precise
implementation for you.

Robert







On Fri, Jan 29, 2010 at 1:28 AM, Manny S <[email protected]> wrote:
> Hi All,
> First off, thanks for your time. A quick noob question on the right way to
> model data.
> I have a table with four columns A,B,C, D.  D - the fourth is of type text
> (contains quite a bit of data).
> I wanted to ensure that the contents of the details column 'D' is not
> fetched during a query. A sample scenario
> User does a search. Sees Columns A,B,C. If they need more details for that
> particular record Click on a link that fetches D for that particular
> record.
> So I tried to do something like - Select A, B, C from tablename.
> I found from the documentation that the GQL query returns full data
> objects and so all queries start with SELECT *.  Is this true for JDOQL on
> the datastore as well? Does this mean everytime I query the data store its
> going to return all columns consuming bandwidth?
> Also since I want the content of COlumn D to be fetched on subsequent user
> action so should I instead create two tables one with
> ID_TB1, A, B, C
> and the other one with
> ID, ID_TB1, D?
> Manny
>
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