I got an answer to the below questions in this thread: http://groups.google.com/group/google-appengine/browse_thread/thread/dc2dcf2e71bc1055 but was recommended to ask here also. Here goes...
I try to figure out how easy it is to ruin/break the data in app engine's datastore by accident (using JDO). Assume that a class, say MyClass, has a number of "persistent" members, e.g. ... int a int b int c ... and assume a number of MyClass objects have been stored in app engine's persistent storage. Now, what will happen if... 1) a new persistent member variable, int d, is *added* to MyClass? The old objects in datastore did not have this variable, so what will their d-value be when they are fetched from datastore? 2) a persistent member variable, int b, is *removed* from MyClass? I guess the b field will be removed from all stored MyClass objects? If not, what will happen if b is re-added at some later point in time? Will the stored MyClass objects now get their old b-value back? 3) the type of a persistent member variable is changed, e.g. if a is converted to a String? What will the value of a be when the already stored objects are fetched from datastore? By the way: the app engine docs focuses on JDO as the interface to the datastore. Is JDO particularly superior to the alternatives? (JPA, Objectify, Twig, SimpleDS, Slim3) -- 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.
