Dan, That is a very good summary of what I am looking for. I will write some tests. Your description of the problem is spot on. Much clearer than anything I've written :)
I also hope that the designers of the datastore thought of this. I fully expect that they have. I just need to confirm it. F On 17 May 2015 at 14:26, Dan Dubois <[email protected]> wrote: > Hi Francis, > > I think I understand exactly what you mean and it's an interesting edge > case when designing the datastore transaction system. > > Somehow within a transaction it needs to record that the 'put' method > either expects the entity it is saving to already exist or not exists. > What's more this logic needs to kick in only if earlier in the transaction > a 'get' bothered to detect if the entity existed in the first place! > > I hope the designers of the datastore considered this and am sure they > have as I have not seen anything to suggest transactional integrity has > ever been broken in my apps. I guess you are looking for confirmation > though as the way the datastore's internals are described in various don't > suggest the edge case is catered for. > > Maybe you could write a test and run it a reasonable number of times to > see if atomicity guarantees break. I would be interested in seeing the > results. > > Dan > > -- > You received this message because you are subscribed to a topic in the > Google Groups "Google App Engine" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/google-appengine/NagJ97YExB0/unsubscribe > . > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/google-appengine. > To view this discussion on the web visit > https://groups.google.com/d/msgid/google-appengine/3a95db7e-e123-4625-a7f2-916d9f627f23%40googlegroups.com > . > For more options, visit https://groups.google.com/d/optout. > -- Francis Stephens Software Developer @ Belua -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/google-appengine. To view this discussion on the web visit https://groups.google.com/d/msgid/google-appengine/CAG1f2XD583M-bHnrOk_fNOW7t8jm1%3DKFRxovTqFqsAYc1vvn%2Bw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
