Good point. I had unconsciously assumed that a replicated memcached solution would be much more efficient than a replicated data store solution, but if the replication and not the disk I/O is what's expensive, then that assumption falls down.
Generally speaking, I'm having difficulty architecting my own app in such a way that it's robust across instances that may be "very distant" from one another. Right now I'm relying on optimistic concurrency in the datastore, but it means my app is much slower than, say, a single instance that held everything in RAM. It's been tempting to just drop the datastore entirely and limit myself to a single instance, but GAE doesn't seem designed to scale down that way; front end instances spin up apparently for no reason, and back end instances, as this thread reveals, seem to have more performance limitations than one would expect, so I have no idea whether a single instance would actually be able to service my user base. - Kris On Friday, August 10, 2012 2:30:35 AM UTC-7, Joakim wrote: > > By *guaranteed*, do you mean that this should be kept synchronized across > multiple data centers? I ask because in the case of a data center > emergency, your app spins up at a different data center. The HR datastore > is always in sync, the memcache is always local to the DC. > Comparing the put-latency of the datastore and memcache for the last few > days, the datastore generally keeps under 50 ms while memcache tends to > stay below 30 ms. I'd say the datastore isn't so bad, and adding sync to > memcache would probably bring that number up a bit. At that point, this new > feature is starting to look a bit like the current HR datastore. Add > properties for insertion date/time etc, and it could be a queue, right? > > I don't mean to shoot you down, but to make you specify what it really is > you want, and how it relates to the current offering. > > -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine/-/z6MbQajkRboJ. 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?hl=en.
