Hi all, As the following document(54p) says, journal and last committed timestamp are co-located with a root entity of an entity group. http://snarfed.org/space/datastore_talk.html
But, an entity group that does not have a root entity seem to support transaction. How does it work? I tried the following code on production server: DatastoreService ds = DatastoreServiceFactory.getDatastoreService(); Key parentKey = KeyFactory.createKey("Parent", 1); Key child1Key = KeyFactory.createKey(parentKey, "Child", 1); Key child2Key = KeyFactory.createKey(parentKey, "Child", 2); Transaction tx1 = ds.beginTransaction(); ds.put(tx1, new Entity(child1Key)); Transaction tx2 = ds.beginTransaction(); ds.put(tx2, new Entity(child2Key)); tx1.commit(); try { tx2.commit(); } catch (ConcurrentModificationException e) { System.out.println( "An entity group that does not have a root entity supports transaction."); } try { ds.get(parentKey); } catch (EntityNotFoundException e) { System.out.println("There is no root entity."); } ds.delete(child1Key); App Engine SDK version:1.2.8 Thanks, Yasuo Higa -- 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.