This has come up a number of times in the past. Timestamps are based on the clock on the server running your Python code. Google makes no official guarantees about clock skew in the cluster, although presumably they are all NTP synchronized. In practice, 30s of overlap is going to work 99.9% of the time. I wouldn't trust anything less than 10s through - people I trust have observed multiple seconds of skew in the system.
Jeff On Sun, May 5, 2013 at 12:13 PM, Pertti Kellomäki < pertti.kellom...@gmail.com> wrote: > Hi again Vinny, > > A related question about implementing pull updates. I would like to pull > only the updates since the previous pull, but if possible I would like to > avoid recording which updates have been delivered to each client. > > How much can I trust the datastore timestamps (i.e. auto_now)? The hrd is > eventually consistent, and from what I've read "eventually" means "within a > few seconds". Would I be in the clear if I post the server side timestamp T > returned by the previous poll, and the server replies with all updates with > timestamps from say T-30s up to now? So if the client polls once a minute, > it polls 90 second time windows at 60 second intervals. Any duplicates > would be dealt with by the client. > -- > Pertti > > > -- > 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 google-appengine+unsubscr...@googlegroups.com. > To post to this group, send email to google-appengine@googlegroups.com. > Visit this group at http://groups.google.com/group/google-appengine?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- 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 google-appengine+unsubscr...@googlegroups.com. To post to this group, send email to google-appengine@googlegroups.com. Visit this group at http://groups.google.com/group/google-appengine?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
