Do you really need one instance of the attribute? If so I suggest unowned, and use transactions to avoid duplicates. Read this artical: http://code.google.com/appengine/docs/java/datastore/transactions.html If performance is not a concern, use a one-many http://code.google.com/appengine/docs/java/datastore/relationships.html
If you do not care about one instance of the attrbite, use a collection. This will also perform better as you only load one entity. http://code.google.com/appengine/docs/java/datastore/dataclasses.html#Collections On Aug 26, 12:23 pm, mar_novice <[email protected]> wrote: > Situation.. > I have two class, Car and Attribute > A car can have zero or more attributes and Cars can have the same > attribute. > > Now for example > I created an instance of a car names X and has an attribute of Big. > ------------------ --------------------------------- > | Car | | Attribute | > ----------------- ---------------------------------- > | X | | Big | > | | | > | > > now what if I created another instance of a car named Y and it has > also an attribute of Big and Fast.. > > ------------------ --------------------------------- > | Car | | Attribute | > ----------------- ---------------------------------- > | X | | Big | > | Y | | Big | > | | | Fast | > > What is the proper approach so that the Big instance of attribute will > not be duplicated? And should I use one to many relationship? Also it > is owned or unowned? > > Thanks in advance for helping out.. > > -mar_novice --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en -~----------~----~----~----~------~----~------~--~---
