I'm implementing a trading system which has function like user A can transfer some money to user B. In RMDB, I would put a transaction so that the balance for user A and user B both changed or neither changed. Since the transfer can happen between any of two users, I cannot image how to define entity group to make transaction work in this case. So my question is: 1. Do I need a transaction here? If needed, how to define entity group to make it work? 2. I have an implementation without using db.run_in_transaction listed below, is this going to work without meeting transaction issues?
accounts = Account.get_key_by_name([key_name_a, key_name_b]) a, b = accounts a.balance -= money b.balance += money db.put(accounts) --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
