数据存储-具有自己类型的Java类

Question

I want to create a class type that has n-children of same type and one parent of same type as members. Every child class will have n-children and one parent. If I persist this model in datastore, will it be costly resource wise? Because each child has n-children and so on.

Say,

@PersistenceCapable
public class Human {

    @Persistent
    List<Human> children;

    @Persistent
    Human parent;

    //the getters and setters
    //null checks
    //add child to list
    //add parent
}

public class Test {
    public static void main(String[] args){
    Human parentHuman = new Human();
    Human childHuman = new Human();

    parentHuman.addChild(childHuman);
    childHuman.addParent(parentHuman);

    Human newChildHuman = new Human();
    newChildHuman.addParent(childHuman);
    newChildHuman.addChild(//another child);
    }
}

I must also be able to get the number of children a human object has at any point of time and also the number of children of their children.

So will storing this type in Datastore create new entities for every child or will it refer to entity of the human object and reuse it?

If my question is not explanatory enough I can put some more light into my question. Any help/suggestion would be much appreciated. Thanks

Answer 1

The answer, in general, is that no, as long as you are using keys to establish relationships between entities, you will be safe from unnecessary inline duplication. Always use keys for entity relationships. For JDO, the specifics can be found here.