q = db.Query(PrimaryData)
q.filter('SheetMetadataId', metadata.getSheetId())
return q.fetch(2000)

Hi Ikai, even the above query takes 3.3 ~ 3.6 seconds. The number of
entities returned by the query is 1261.
I'm using Expando model, the total number columns for this particular
set of entities are 25.
Yes. I've created composite index. Here is the index definition.

- kind: PrimaryData
  properties:
  - name: SheetMetadataId
  - name: InstanceAssignedTo

please let me know if you need more information.


On Mar 17, 11:50 pm, "Ikai Lan (Google)" <ika...@google.com> wrote:
> If you have a composite index, the performance of this query should be
> mostly linear (find start location of index and just return min(2000, number
> of entities that satisfy query from there on out) number of keys and items.
> If you only have individual indexes for SheetMetadataId as well as
> InstanceAssignedTo, this uses zigzag merge join, where performance can
> greatly vary depending on the shape of the data.
>
> Just out of curiosity, what is the performance of this query?
>
> q = db.Query(PrimaryData)
> q.filter('SheetMetadataId', metadata.getSheetId())
> return q.fetch(2000)
>
> If it's in a similar ballpark, my other guess is that the query takes that
> amount of time because the entities are large.
>
> You mentioned created a composite index. Can you post that?
>
> I'll talk to the datastore team to see what we can do to provide something
> similar to EXPLAIN plans for queries.
>
> Ikai Lan
> Developer Programs Engineer, Google App Engine
> Blog:http://googleappengine.blogspot.com
> Twitter:http://twitter.com/app_engine
> Reddit:http://www.reddit.com/r/appengine
>
>
>
>
>
>
>
> On Thu, Mar 17, 2011 at 10:07 AM, adhi <adhinaraya...@gmail.com> wrote:
> > Hi Robert,
> > I've not used reference properties. Its a simple query and it'll be
> > like this.
>
> > q = db.Query(PrimaryData)
> > q.filter('SheetMetadataId', metadata.getSheetId())
> > q.filter('InstanceAssignedTo IN',
> > [u'User_c42e8919_448e_11e0_b87b_f58d20c6e2c3',
> > u'User_1fd87ac5_073d_11e0_8ba1_c122a5867c4a'])
> > return q.fetch(2000)
>
> > and I replaced the IN filter to '=' with single value. Still its
> > taking same time.
>
> > On Mar 17, 6:27 am, Robert Kluin <robert.kl...@gmail.com> wrote:
> > > Use Appstats. It may not be the query that is slow.  If you are using
> > > reference properties, perhaps you are dereferencing them.  If you
> > > should us the query and how you're using the results we might be abel
> > > to give more suggestions.
>
> > >http://code.google.com/appengine/docs/python/tools/appstats.html
>
> > > Robert
>
> > > On Mon, Mar 14, 2011 at 10:54, adhi <adhinaraya...@gmail.com> wrote:
> > > > Hi, I'm running a query in appengine which is returning just 1200
> > > > entities, but its taking 3.5 seconds. The query doesn't contains
> > > > inequality filters, but anyway I added index for that. Can anyone tell
> > > > me how to analyse this and improve theperformance?
>
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