Is Apple in-app-purchase transaction_id globally unique?

Question

Are Apple in-app-purchase transaction_ids unique only for a given app or product, or are they in fact globally unique?

Example: If a transaction_id (eg 1000000019169002) exists for an application A, is it possible for that transaction_id to again be returned for a different transaction against a second application B?

Answer 1

In the purchase info you will get both prodcut_id and transaction_id, so if you verify both together it will be guaranteed unique. It´s not possible to find any information about the transaction_id uniqeness alone.

You can also see the In-App Purchase Programming Guide for more information.