The master/slave datastore has a single master, so there are not consistency issues like you would have with multi-master replication.
The high-replication datastore is based on PAXOS; basically it requires a 'majority' of the masters receive and accept a write. That effectively makes it possible to detect conflicts at write (and read) time at the expense of higher write (read) latencies. Robert On Wed, Apr 13, 2011 at 19:09, PT <[email protected]> wrote: > Hello, > I'm trying to wrap my head around the Appengine and its cloud architecture. > > So if I have a program based on this large database where a multitude of > users around the world edit and update lets say a city map. > As I understand it right now peoples actions are applied not to the database > itself (as in being the sole one) but to "clones" of it distributed around > the world and which are synchronized realitively quickely. > > So taking my example, what happens if a person in France adds a building on > the map while an other edits its color and someone else changes its name all > of this while an other group of people in Australia (thus working on an > other clone of the DB) at the very same time edit different information on > the very same grid coordinates, and then imagine 5 other groups around the > world doing the same thing. What would actually happen ? > > I'm asking this as I've read in other threads about the Appengine that even > it has a strong integrity of its information it comes at a cost of its real > time handling of events. So is this true and how much so ? > > Thanks for any answers ;) > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" 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?hl=en. > -- You received this message because you are subscribed to the Google Groups "Google App Engine" 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?hl=en.
