changing an entity's entity group with existing data

[doright]

I run an app on GAEJ, using JDO.  It's been live and has had paying customers for over a year now. It using master/slave but I'm considering migrating to HRD.

Having just watched the "more 9's please" vid:

http://www.google.com/events/io/2011/sessions/more-9s-please-under-the-covers-of-the-high-replication-datastore.html

I'm considering taking the advice and putting pretty much all of my entities into a single group.  It is after all an enterprise app - so performance should be fine for my throughputs.  So my question is:

- what happens to existing data if I go and change the entity group of an entity?  Or more specifically do I need to manually migrate data to a different node if I wanted to update an entity's group?

- and a secondary related question.  It's a multi-tenancy application, so I'm assuming that data in different namespaces is automatically separated into different entity groups even if they belong to an entity that is part of a group.

ie Reservation and ReservationDetail are part of the same entity group. However I assume that there is a different entity group for these in each of my namespaces?

[Jeff Schnitzer]

On Tue, Mar 20, 2012 at 4:53 PM, doright <doug.s...@gmail.com> wrote:
> So my question is:
> - what happens to existing data if I go and change the entity group of an
> entity?

Just to offer some clarification on this point: You cannot "change"
the entity group of an entity. The entity group is part of what
defines the key of an entity. What you can do is create a new entity
(with a new key) and delete the old entity, but you will have to
adjust any stored foreign keys as well.

Jeff