This would mean really a lot of updates. E.g. - User1, 1 jan 2009, 1000 - User1, 1 feb 2009, 1100
This would mean craeting an avarage usage of 100 for jan 2009. Now next time the user enters a meter reading is e.g. 1 jan 2010 with value 2300. This would mean in this case createing avaerage use valuues for feb, mar, apr, may, jun, jul, aug, sep, okt, nov and dec 2009. And als updating average usage of all users. In a SQL join this would be less dificult and error prone to implement. I'm wondering if my use case fits the BigTable principles and thus GAE, or that I would be better of with a realtional database. But this would mean I can't use GAE and have to go for another cloud solution like mor.ph On 7 apr, 06:36, GregF <[email protected]> wrote: > On Apr 7, 6:53 am, Marcel Overdijk <[email protected]> wrote: > > > - User1, 1 jan 2009, 1000 > > - User1, 1 feb 2009, 1100 > > - User1, 1 mar 2009, 1200 > > The avarage will be 1100 *** > > > But maybe the user misses registering the meter reading on 1 feb: > > - User1, 1 jan 2009, 1000 > > - User1, 1 mar 2009, 1200 > > The average will still be 1100 *** > > I guess the answer will be to store average values when creating (and > > updaing existing) meter reading records. > > But how should this be implemented? > > *** Corrected. > > Yes, calculate averages when you update the table. If you don't need > to search for particular readings, you might want to store the meter > readings in a db.ListProperty(int), with an associated db.ListProperty > (int) of timestamps. > > I need to count various things in my app, so I define a model and > helper functions like this: > > class Counter(db.Model): > count=db.IntegerProperty(required=True,default=0) > > # Increment a counter > # NB: These are functions, not class members > def _incrementCounter(counterId,amount): > counter=Counter.get_by_id(counterId) > counter.count+=amount > counter.put() > def incrementCounter(counterId,amount=1): > db.run_in_transaction(_incrementCounter,counterId,amount) > > I'm sure you can do something similar for your averages. --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
