If you're trying to infer some type of statistical information from the dataset after it has been stored, then this might be difficult, especially in the absence of background/offline processing.
However, here is something you might want to try, for the particular scenario you describe: 1. Create an indexable property for each entity/entry as you store it. Looking at your data, it looks like the timestamp is sufficient, because each entry has a unique timestamp so you won't have to worry about breaking ties. 2. You now want to fetch 1000 entities at known intervals. So extrapolate the timestamps of where those entities fall and fetch them. Unfortunately, this means that you have to make 1000 queries (I believe the datastore queues queries up, to a max of 35), so you might have to do this in multiple requests, and append the entities you fetch each time to a list. On Sep 25, 11:46 am, Savraj <[EMAIL PROTECTED]> wrote: > So I have stored some data in the app-engine database, with new data > every 5 seconds. > > example dataset: > > ID - Time - Value > 1 - 9/20/2008 16:00:00 - 100 > 2 - 9/20/2008 16:00:05 - 120 > 3 - 9/20/2008 16:00:10 - 130 > 4 - 9/20/2008 16:00:15 - 250 > ....... > 17278 - 9/21/2008 15:59:60 - 200 > 17279 - 9/21/2008 15:59:55 - 100 > 17280 - 9/21/2008 16:00:00 - 220 > > How do I get just 1000 values back that cover the entire recorded > period, so I can put them in a chart? What sort of query should I > construct? I imagine it's something like, 'give me every 20th value' > -- but how do I express than in a query? > > Thanks in advance for your kindness and consideration. > > - s --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
