ok i just tested the 2 operations with appstats and there is the same amount of rpcs for both. and i dont see any significant speed difference too.
so the conclusion is that if you want to fetch the latest 100 entities you use fetch(100), if you want to filter in memory and do checks on all entities you can do it without fetching the entities. would appreciate any comment on this topic to understand it better. thx On Jan 4, 2012, at 4:30 PM, Andreas wrote: > but there are no cursors in this query. and nothing is actually 'fetched'. > > lets say i have 2000 entities and i want to iterate over those 2000. > > what causes more load? fetching of not fetching? or is it the same? > > > On Jan 4, 2012, at 4:27 PM, Renzo Nuccitelli wrote: > >> Because if you know the desired number of results in advance, fetch >> is faster than iterating over query when you are using cursors. You >> can read it on documentation: >> http://code.google.com/intl/en/appengine/docs/python/datastore/queries.html#Query_Cursors >> just above Limitations of Cursors. >> >> On 4 jan, 17:46, Andreas <[email protected]> wrote: >>> good question! >>> >>> On Jan 4, 2012, at 12:53 PM, Kostya wrote: >>> >>> >>> >>> >>> >>> >>> >>>> Hi, >>> >>>> why I need to use the fetch() instance method if every query can >>>> return an iterator and I can access the results of a query by >>>> iterating over it: >>> >>>> authors = db.Query(Author).filter('name =', 'Kostya') >>>> for i in range(10): >>>> print authors[i].name >>> >>>> instead: >>> >>>> authors = db.Query(Author).filter('name =', 'Kostya') >>>> authors.fetch(10) >>>> for author in authors: >>>> print author.name >>> >>>> -- >>>> 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 >>>> athttp://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]. >> 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]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
