Hi Jon,
1) When you build a query you can specify the ancestor.
PageIndex.all(keys_only=True).ancestor(thepage)
http://code.google.com/appengine/docs/python/datastore/queryclass.html#Query_ancestor
2) I would not add multiple list properties to the same model. I
would also probably not make different kinds in this case.
Personally, depending on exactly how you will need to query and
maintain the data, I would either just put each field in the same
"search" list or make a PageIndex entity for each type.
Robert
On Wed, Sep 1, 2010 at 02:39, ogterran <[email protected]> wrote:
> Couple more questions
> 1. If I have the parent entity, how do get all the child entities?
> 2. If I have more fan out lists, so usernames is one, but now i have
> emails and ipaddresses
> is it more efficient to create different entity kinds or just add
> another list to PageIndex?
> i.e.
> class PageIndex(db.Model):
> usernames = db.StringListProperty(required=True)
> emails = db.StringListProperty(required=True)
> ipaddreses= db.StringListProperty(required=True)
>
> or
>
> class PageIndex(db.Model):
> usernames = db.StringListProperty(required=True)
> class PageEmailIndex(db.Model):
> emails = db.StringListProperty(required=True)
> class PageIpAddressIndex(db.Model):
> ipaddreses= db.StringListProperty(required=True)
>
> Thanks
> Jon
>
>
> On Aug 31, 11:19 pm, ogterran <[email protected]> wrote:
>> Thanks guys for all the responses.
>> I checked out Brett's presentation and he talks about this exact issue
>> on how to optimize using list properties
>>
>> So following the Brett's presentation, create 2 entitiy kinds.
>> Page and PageIndex where Page is the parent of PageIndex (specify
>> parent in PageIndex constructor)
>>
>> class Page(db.Model):
>> pagekey= db.StringProperty(required=True)
>>
>> class PageIndex(db.Model):
>> usernames = db.StringListProperty(required=True)
>>
>> indexes = db.GqlQuery("SELECT __key__ FROM MessageIndex "
>> "WHERE usernames = :1", username)
>> keys = [k.parent() for k in indexes]
>> pages = db.get(keys)
>>
>> Since we are querying by key, it is 10x faster, and no unnecessary
>> serialization.
>> We can fan out by adding multiple PageIndex, if reaches 5000 max.
>>
>> Is this about right?
>>
>> Thanks
>> Jon
>>
>> On Aug 31, 9:34 am, Jeff Schwartz <[email protected]> wrote:
>>
>>
>>
>> > A list property's size is limited to 5000.
>>
>> > If you only want to know if a user has visited a page, you can use the
>> > first
>> > model & query it returning only keys to avoid list serialization issues. In
>> > addition, key only queries are very fast.
>>
>> > Additionally, if your Page model's key had a string name that was the
>> > pagecode then you could even use the key to identify the page. In other
>> > words, you'd be materializing the view in the key of the model. This would
>> > eliminate the need to serialize the entity entirely when it is used for
>> > lookup.
>>
>> > Writing out the entity after having updated its list property is another
>> > story all together as writes are subject to fail due to contention. To
>> > reduce the odds of contention you can shard your model by a factor of 10 or
>> > 20 to reduce but not eliminate the possibility of contention.
>>
>> > There are a number of Google IO videos on YouTube that you can watch which
>> > cover these techniques.
>>
>> > Jeff
>>
>> > On Tue, Aug 31, 2010 at 5:22 AM, ogterran <[email protected]> wrote:
>> > > Hi,
>>
>> > > I have a choice to store the data two ways. Which way is more
>> > > efficient when querying in BigTable?
>>
>> > > First way:
>> > > class Page(db.Model):
>> > > pagekey= db.StringProperty(required=True)
>> > > usernames = db.StringListProperty(required=True)
>>
>> > > So all the users who visits the page, will be added to the username
>> > > list
>>
>> > > Second way:
>>
>> > > class Page(db.Model):
>> > > pagekey= db.StringProperty(required=True)
>> > > username = db.StringProperty(required=True)
>> > > All the users who visits the page will have its own row
>>
>> > > The query will be with both username and pagekey.
>> > > There can be a lot of users.
>> > > Is there a limit on theStringListsize?
>> > > what are the advantages of each methods of storing data?
>>
>> > > Thanks
>> > > Jon
>>
>> > > --
>> > > 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%2Bunsubscrib
>> > > [email protected]>
>> > > .
>> > > For more options, visit this group at
>> > >http://groups.google.com/group/google-appengine?hl=en.
>>
>> > --
>> > --
>> > Jeff
>
> --
> 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.
