Question

I’m creating a object with JDO and let the GAE set the Key for me.

    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Key key;

As results of the PersistenceManager.makePersistent(myObject), I have a key with a long value that seem to be ordered. I have alread looking for on GAE documentation, but I cannot find where that is explicity documented. Is this genereated key ordered by creation?

I know that is not incremental.

Answer 1

AFAIK keys are assigned in ranges. See DatastoreService.allocateIDs().

As far as I have observed, each instance gets a range. So when entities are created IDs are icremental within a range, but they are not ordered as they come from different ranges.

I’m guessing: you are trying to find out which entities are new? Add a timestamp property then check for updates via cursors.