google-cloud-datastore

I have an application deployed in Google app engine. I am getting inconsistent data when i fetch an entity by id immediately after updating that entity. I'm using JDO 3.0 to access the app engine datastore. I have an entity Employee @PersistenceCapable(detachable = "true") public class Employee implements Serializable { /** * */ private static final long serialVersionUID = -8319851654750418424L; @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY, defaultFetchGroup = "true") @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true") private String id;

Suppose we have 5 entities: A,B,C,D,E with the following ancestor hierarchy: A / \ B C / \ D E I have two questions about this: Do we have 2 entity groups here (A,B,D) and (A,C,E) or just 1 entity group (A,B,C,D,E)? If we want to update entities D and E, can we update each of them 5 times per second or should the combined writes for D,E not exceed 5? Xion There is only one entity without a parent here - that is, A. It is therefore a root entity of the sole entity group that contains A, B, C, D and E. Entity group is simply a distinct tree of entities linked by parent-child relationship. As for

I have the following heriacy. GrandParent --> Parent --> Child Parent and Child use @Parent Ref<GrandParent> and @Parent Ref<Parent> to create there parent relationship. I am trying to come of with a good way to do a cascading delete for GrandParent . I of course I could load all the children, generate keys from them and delete by key. This seems terribly inefficient. Is there something where I could query by parent and turn the query results into a list of keys without having to do the full fetch? Any thoughts, or third party libraries welcome. Basically, what Michael said, but here is the

I have been reading all over stackoverflow concerning datastore vs blobstore for storing and retrieving image files. Everything is pointing towards blobstore except one: privacy and security. In the datastore, the photos of my users are private: I have full control on who gets a blob. In the blobstore, however, anyone who knows the url can conceivable access my users photos? Is that true? Here is a quote that is supposed to give me peace of mind, but it's still not clear. So anyone with the blob key can still access the photos? (from Store Photos in Blobstore or as Blobs in Datastore - Which

I noticed that the children of PersistentUser are not deleted when using the JPQL query below. However, the children are deleted if I perform an entityManager.remove(object) . Is this expected? Why doesn't the JPQL query below also perform a cascaded delete? @OneToMany(mappedBy = "persistentUser", cascade = CascadeType.ALL) private Collection<PersistentLogin> persistentLogins; ... @Override @Transactional public final void removeUserTokens(final String username) { final Query query = entityManager.createQuery( "DELETE FROM PersistentUser p WHERE username = :username"); query.setParameter(

I am in the early stages of developing a sports statistics website (ultimate frisbee) and would like to know your opinions if Google App Engine is right for me. I am writing it in Python using Django and have been comfortable with standard RDBMS for years but this site is a long term project and I am expecting very large amounts of data so I would like the "infinite" scaling that the GAE datastore offers. A vast majority of the queries to the database will return very standard results that would make the datastore seem like a logical choice. However, I would like to be able to make extremely