> The behavious of DataNucleus depends on the strategy I choose to generate the > @Id field.
Obviously, as per DN docs (and why I asked you to show your class) :- If using pessimistic txns, then all persist/update/delete operations happen immediately. Consequently it doesn't matter which value generator strategy you choose you always get an identity immediately after the persist. If using optimistic txns, then all persist/update/delete operations are queued until flush/commit, so we do them in a block. If you chose a value generator strategy of IDENTITY then this can only happen during persist (by definition), so is delayed. If you chose any other value generator strategy then you get your identity immediately since it doesn't require a persist. Google have the opportunity to define their own value generator strategies in *their plugin*. They also provide "SEQUENCE" strategy which you could use, and get your identity immediately after a persist. At the end of the day the JPA (and JDO too) specs say that no identity is guaranteed until flush, and anyone writing a portable application should follow that rule (and not pick and choose what they feel like following). It doesn't matter if some implementations just happen to do one thing or another, it is not covered by the spec so you cannot guarantee it. There are many things that DN does that Hibernate, EclipseLink and OpenJPA don't do ... but does that mean they should copy us ? Of course not. Implementors follow a spec for a reason, because its behaviour is guaranteed. PS1. Whilst EclipseLink is "Reference Implementation" for JPA, that actually means very little on its own. It simply means that it is proof that the spec is implementable. DataNucleus is "Reference Implementation" for JDO, but doesn't mean that any other JDO impl should copy how we do things. PS2. Use of AUTO (JPA) / NATIVE (JDO) is not to use IDENTITY since not all datastores support such a thing. PS3. GAE/J's plugin uses such an old version of DataNucleus (we're currently at version 2.1, whereas you use 1.1) that we don't actually support any such usage now, hence why I don't monitor this forum, and only post here when i just happen to have some spare time. -- 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 google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
