The entity id (or name) is known / available after a put(). Fred on my Android. On Sep 3, 2011 2:47 AM, "NM" <nirmallya.mukher...@gmail.com> wrote: > In case of a wizard based interface with multiple steps where users > provide data at every step we have to ensure that we work off session > data. By and large we can conclude that the following design in the > application will help alleviate the eventual read consistency scenario > in HR which is not a problem in M/S. > 1. If the appointment (or any object) is created/updated in step 1 it > also needs to go in the user session (I am a Java developer) > 2. Step 2 gets the appointments (or any object collection) from the > data store and checks if the object created in step 1 is present. If > not add it in the collection manually > 3. Pass it on to the JSP for display > > We have to live with the fact that all appointments will not show if > the calendar is global where appointments created by multiple users > need to be displayed. > > I was also wondering if Bigtable/Datanucleus can let the program know > the newly generated PK like a traditional relational database. If we > can get the PK then the process of checking the collection becomes > simple in addition to other benefits of knowing the PK after insert. > > Finally how much latency are we really talking about between the last > write and the consistent read? > > On Sep 2, 10:11 pm, Fred Sauer <fre...@google.com> wrote: >> On Fri, Sep 2, 2011 at 12:18 AM, NM <nirmallya.mukher...@gmail.com> wrote: >> > Here is a usecase that may support M/S over HRD. >> >> > I have a form where we capture appointment information such as date, time >> > and some other details. Upon a successful save the resulting page is a >> > calendar view that needs to read all appointments including this newly >> > created appointment. >> >> > Given this and eventual consistency mode of HRD the calendar at times does >> > not show the newly saved appointment. When I refresh the screen after a few >> > seconds it does; obviously by then the data would have replicated. This is >> > obviously not an issue with M/S. >> >> > Thoughts? >> >> The calendar times you are querying are all for one user, you could put the >> calendar entities in a single entity group and then use an ancestor query, >> which will return consistent results. >> >> If you need to query across entity groups, but still want the calendar entry >> you just saved to be included in the results, then the recommended approach >> is: >> - Perform your cross entity group query in the normal way >> - In your application code, insert the just inserted entity into the result >> set if it's not there >> - Show the user the merged result set >> >> You can store away or track the "just inserted calender entity" in a cookie, >> in a url / form parameter, in memcache, or in an HTTP session object (Java). >> >> Fred >> >> > -- >> > 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/-/lC6R_999_vQJ. >> >> > To post to this group, send email to google-appengine@googlegroups.com. >> > To unsubscribe from this group, send email to >> > google-appengine+unsubscr...@googlegroups.com. >> > For more options, visit this group at >> >http://groups.google.com/group/google-appengine?hl=en. >> >> -- >> Fred Sauer >> Developer Advocate >> Google Inc. >> 1600 Amphitheatre Parkway >> Mountain View, CA 94043 >> fre...@google.com > > -- > 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 google-appengine+unsubscr...@googlegroups.com. > For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en. >
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