The URL I posted earlier in the thread explains it, but here's a little bit
more detail:
A parent entity plus a kind defines an id-space, so entities with the same
parent and the same kind are guaranteed to have unique ids. For example, if
you have an Entity with
Parent:A
Kind: Person
Id: 10
you are guaranteed that no other entity with Parent A and Kind Person will
be assigned an Id of 10. However, an entity with a different Parent and
Kind Person or an entity with Parent A and a different Kind _can_ be
assigned an Id of 10. The datastore pre-allocates batches of ids across
multiple servers under-the-hood, so you can't make any assumptions about the
Id that will get assigned in terms of contiguousness. The only safe
assumption is that the id will be unique for that Parent/Kind combination.
Hope this helps,
Max
On Thu, Sep 10, 2009 at 5:29 AM, iker98 <ike...@gmail.com> wrote:
>
> Definitely I don't understand the number ID generator behavior across
> kinds (in prod datastore). Does anyone know any URL with detailed
> explanation about it?
>
> Thanks
>
> On Sep 9, 11:58 am, Tica2 <petrica.chir...@gmail.com> wrote:
> > Max,
> >
> > I like to have same behavior between local and production environment
> >
> > It is posible ?
> >
> > For instance the code:
> >
> > StringBuffer sb = new StringBuffer();
> > KeyRange range = ds.allocateIds("a", 2);
> > for (Key key : range) {
> > sb.append("\n a " + key.toString());
> > }
> >
> > range = ds.allocateIds("b", 2);
> > for (Key key : range) {
> > sb.append("\n b " + key.toString());
> > }
> >
> > Key parentKey = KeyFactory.createKey("c", 1);
> > sb.append("\n c " + parentKey.toString());
> >
> > range = ds.allocateIds(parentKey, "d", 2);
> > for (Key key : range) {
> > sb.append("\n d " + key.toString());
> > }
> > System.out.println(sb.toString());
> >
> > Local produce:
> > a a(1)
> > a a(2)
> > b b(3)
> > b b(4)
> > c c(1)
> > d c(1)/d(5)
> > d c(1)/d(6)
> >
> > But in production environment:
> >
> > a a(1)
> > a a(2)
> > b b(1001)
> > b b(1002)
> > c c(1)
> > d c(1)/d(1)
> > d c(1)/d(2)
> >
> > a a(1003)
> > a a(1004)
> > b b(3)
> > b b(4)
> > c c(1)
> > d c(1)/d(1001)
> > d c(1)/d(1002)
> >
> > Thanks
> >
>
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