Have a look at the Datastore "Key" thingy. The keys generated are unique across the system IMO. Not sure though but that's what I remember reading somewhere.
-N On Dec 29, 7:43 am, MG <[email protected]> wrote: > Hello! > > I need to create a global atomic counter (64-bit) in my AppEngine/J > app. Like > > long count = MyCounter.increment() > > that will 100% guarantee that count will never ever be the same for > two different requests, and that I will be able to increment it > several million times/day initially, and much more if/when traffic > increases. I do not really care if it skips a number or two > occasionally: I can live with it returning a value larger than the > actual number of calls, but I do need absolute uniqueness and > reasonably linear growth (i.e. is two consecutive calls from a client > should result in ascending counter values). > > Is this possible to do with Google AppEngine? Sharded counters can > ensure consistent counting, but not unique counts; memcache counters > can ensure unique increments, but they are perishable and thus > difficult (impossible?) to properly synchronize with persistent > storage. Using one entity to read-update in a transaction will not > scale... > > Thanks, > MG -- 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 [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
