Just forget everything you know about SQL and you will do just fine. Jeff
On Sat, Dec 4, 2010 at 12:27 PM, YF CAO <[email protected]> wrote: > thanks. > i find objectify project on google code. > in learing, bigtable is most difficult. > > > > 2010/12/5 Jeff Schwartz <[email protected]> > >> Objectify is a thin wrapper library around the native low level java >> datastore api. It adds numerous convenience methods but doesn't stray from >> the low level api. In addition, it allows you to define your models as pojos >> using java annotations for things like numeric and string key ids, >> properties which are keys of a parent, etc. I wouldn't think of using >> anything else. The low level api examples I just gave you map very closely >> to how you would accomplish the same thing in Objectify. >> >> You can read more about Objectify on their wiki at >> http://code.google.com/p/objectify-appengine/wiki/IntroductionToObjectify >> . >> >> Jeff >> >> On Sat, Dec 4, 2010 at 12:05 PM, YF CAO <[email protected]>wrote: >> >>> thanks to Jeff Schwartz. >>> Objectify is very good ! >>> >>> thanks to Erick Fleming too. >>> >>> 2010/12/5 Jeff Schwartz <[email protected]> >>> >>>> Odd but I don't see him needing either cursors or 2 indexes to achieve >>>> his required result and it doesn't even need a filter condition. IMO it >>>> just >>>> requires a descending ordering with a limit of 1. >>>> >>>> On Sat, Dec 4, 2010 at 11:38 AM, Erick Fleming >>>> <[email protected]>wrote: >>>> >>>>> In Java you can use Query cursors to [1] limit your results. As far as >>>>> aggregate functions (like MIN and MAX) you can use [2] indexes to achieve >>>>> the similar result (ie. order by age and get the top result) >>>>> >>>>> [1] >>>>> http://code.google.com/appengine/docs/java/datastore/queriesandindexes.html#Query_Cursors >>>>> <http://code.google.com/appengine/docs/java/datastore/queriesandindexes.html#Query_Cursors> >>>>> [2] >>>>> http://code.google.com/appengine/docs/java/datastore/queriesandindexes.html#Introducing_Indexes >>>>> <http://code.google.com/appengine/docs/java/datastore/queriesandindexes.html#Introducing_Indexes> >>>>> On Sat, Dec 4, 2010 at 10:31 AM, Jeff Schwartz < >>>>> [email protected]> wrote: >>>>> >>>>>> Conceptually they are tables, but not in the same sense as SQL tables. >>>>>> They are more like a hash map and if you think of them in those terms you >>>>>> will be better served. >>>>>> >>>>>> Are you coding in Python or Java. If you are coding in Java then >>>>>> here's an example: >>>>>> >>>>>> query(Some.class).order('age').limit(1).get() >>>>>> >>>>>> >>>>>> On Sat, Dec 4, 2010 at 11:16 AM, Zeynel <[email protected]> wrote: >>>>>> >>>>>>> On Dec 4, 11:08 am, Tim Hoffman <[email protected]> wrote: >>>>>>> > Remember there are no tables. Just kinds representing models. >>>>>>> >>>>>>> I am confused by this statement. When I look at the Development >>>>>>> Console - Datastore Viewer; I see a table named after the model. In >>>>>>> my >>>>>>> case, I have a table called User with columns "userEmail", "userName" >>>>>>> and so on. Each row in this table is what the documentation calls an >>>>>>> "instance" of the class. So what is the justification for the >>>>>>> statement that there are no tables? >>>>>>> >>>>>>> -- >>>>>>> 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]<google-appengine%[email protected]> >>>>>>> . >>>>>>> For more options, visit this group at >>>>>>> http://groups.google.com/group/google-appengine?hl=en. >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> *Jeff Schwartz* >>>>>> >>>>>> >>>>>> -- >>>>>> 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]<google-appengine%[email protected]> >>>>>> . >>>>>> For more options, visit this group at >>>>>> http://groups.google.com/group/google-appengine?hl=en. >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Erick Fleming >>>>> >>>>> -- >>>>> 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]<google-appengine%[email protected]> >>>>> . >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/google-appengine?hl=en. >>>>> >>>> >>>> >>>> >>>> -- >>>> *Jeff Schwartz* >>>> >>>> -- >>>> 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]<google-appengine%[email protected]> >>>> . >>>> For more options, visit this group at >>>> http://groups.google.com/group/google-appengine?hl=en. >>>> >>> >>> -- >>> 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]<google-appengine%[email protected]> >>> . >>> For more options, visit this group at >>> http://groups.google.com/group/google-appengine?hl=en. >>> >> >> >> >> -- >> *Jeff Schwartz* >> >> -- >> 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]<google-appengine%[email protected]> >> . >> For more options, visit this group at >> http://groups.google.com/group/google-appengine?hl=en. >> > > -- > 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]<google-appengine%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine?hl=en. > -- *Jeff Schwartz* -- 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.
