I wrote a simple test app that used both the db and ndb api and deployed it
to app engine. Using appstats I confirmed that both RunQuery when getting
the list of articles.
On Wednesday, July 23, 2014 8:03:40 PM UTC-5, Jay wrote:
>
> I refer you to line 3865 of __init__ in the ext.db package in the sdk.
> This is on a _ReverseReferenceProperty that gets setup.
> If I have time tomorrow I will write a quick test to demonstrate.
>
> On Wednesday, July 23, 2014 11:11:31 AM UTC-5, saintthor wrote:
>>
>> are you sure?
>>
>> i tested in two apps. the first is using query. when i do a query, the
>> read ops increases about 300. the second is using referenceproperty as
>> above, after 5 times showing, there is no obviously increase.
>>
>> the articles in the second app is much more than the first. so i don't
>> think it run a query.
>>
>> 在 2014年7月22日星期二UTC+8下午11时20分14秒，Jay写道：
>>>
>>> When you use that api in db, it is doing a query underneath the covers.
>>>
>>> On Monday, July 21, 2014 11:27:08 PM UTC-5, saintthor wrote:
>>>>
>>>> in db, i set such a property in model article:
>>>>
>>>> auth = db.ReferenceProperty( author, collection_name="AuthSet" )
>>>>
>>>>
>>>> and use author.AuthSet to get all articles written by the certain
>>>> author. there is no query. how can i do the same thing in ndb?
>>>>
>>>>
>>>> 在 2014年7月22日星期二UTC+8上午3时55分28秒，Jay写道：
>>>>>
>>>>> Responding to your first post ... that is right. The parent key is
>>>>> part of the entity's key. When you use get_by_id, this is just shorthand
>>>>> for Key('Foo', 99).get().
>>>>> You cannot get an entity by key unless you know the key, the whole
>>>>> key.
>>>>>
>>>>> You say you don't want to query, but your use case ... "give me all
>>>>> articles for user A" ... sounds like a query.
>>>>> articles = Article.query(Article.author == user_key)...
>>>>>
>>>>> If you want to do something like "most recent n articles" then you can
>>>>> store those keys in a 'secondary index' of sorts and use ndb.get_multi()
>>>>>
>>>>> On Monday, July 21, 2014 8:11:20 AM UTC-5, saintthor wrote:
>>>>>>
>>>>>> to query may cost too many ops. i don't query.
>>>>>>
>>>>>>
>>>>>>
>>>>>> 在 2014年7月21日星期一UTC+8下午8时53分29秒，Kaan Soral写道：
>>>>>>>
>>>>>>> Not associated with google, also not an expert on ndb
>>>>>>>
>>>>>>> As far as I know key groups are related with consistency, in my
>>>>>>> opinion, you shouldn't put article's and author's in the same group,
>>>>>>> there
>>>>>>> is a 1/s write speed limit on entity groups, if you put them in the
>>>>>>> same
>>>>>>> entity group, you could hit this limit more easily
>>>>>>>
>>>>>>> You don't even have to use referenceproperty's - I would just put
>>>>>>> the author key in an article StringProperty named "author" and query
>>>>>>> for
>>>>>>> it, if I were you
>>>>>>>
>>>>>>
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