Hello, When updating a schema on the Google App Engine, new properties don't automatically get applied to the existing entities. So in your particular use-case, you could start out with altering schema and providing values for the newly added properties as and when they are provided. That overhead being taken care of, the data-store saves entities in a manner that aids fast retrieval, hence third option makes more sense.
Refer : http://code.google.com/appengine/articles/update_schema.html App Engine Data Store : http://www.youtube.com/watch?v=tx5gdoNpcZM ~Ic On Sep 15, 7:06 am, Vik <[email protected]> wrote: > hie > > anyone on this please? > > Thankx and Regards > > Vik > Founderwww.sakshum.comwww.sakshum.blogspot.com > > On Mon, Sep 13, 2010 at 10:59 PM, Vik <[email protected]> wrote: > > Hie > > > I have a design question for your advise. > > > I have a feature where i store details of Blood donors in the app engine. > > > We got a requirement where we should be able to mark blood donors inactive > > for some period. So another three things need to be stored is: > > > 1. isActive (true or false) > > 2. InactivityReason (some text) > > 3. ActiveDate (a date at which isActive will be marked again true by a > > schedular). > > > So now there are two ways to store this information > > > First: Having a separate entity with 4 attributes (above 3 plus one blood > > donor entity primary key ). > > > This keeps this related data separate like a 1:1 relation. Updating this > > info will be simple however, to display only active blood donors > > will need a lot of processing. > > > Second: Doing it the same way as above and also adding isActive attribute > > to the Blood Donor entity. so that quering only active donors > > is simple. However, this will make 2 entity updates for marking a blood > > donor inactive. The new entity plus blood donor entity (isActive field) > > > Third: Just adding all the three attributes to the Blood donor entity and > > not creating any new entity type. This keeps doing update as well as > > retrieval of active donors simple but kind of dis-obeys the OOPs or the > > natural logical separation of the information. > > > From GAE scalabilbity perspective what is the right approach? What way we > > should design it. Please advise. > > > Thankx and Regards > > > Vik > > Founder > >www.sakshum.com > >www.sakshum.blogspot.com -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" 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-java?hl=en.
