On Tue, Jun 23, 2009 at 3:27 PM, herbie <4whi...@o2.co.uk> wrote:
>
> Oh, really? That limits my app somewhat. I asume if I have no
> inequality filtres and order by date I will get the latest entities?
>
> I could then filter these in memory for x > threshold
Correct.
-Nick Johnson
>
>
>
>
Oh, really? That limits my app somewhat. I asume if I have no
inequality filtres and order by date I will get the latest entities?
I could then filter these in memory for x > threshold
On Jun 23, 1:50 pm, "Nick Johnson (Google)"
wrote:
> Hi herbie,
>
> If your query includes an inequality (s
Hi herbie,
If your query includes an inequality (such as x>50), then your first sort
order has to be on the same property as that inequality, which means you
can't (directly) fetch the most recent 200 results with x>50. You either
need to change your query to use only equality filters, or you need
Thanks for your help Nick.
No my threshold value 'x' isn't constant. I still havn't got my head
round this yet! Can you tell me how to get the latest entities
(assuming I don't want all of them) out of the datastore and filter
on another property?
For example: Get the latest 200 entities
On Tue, Jun 23, 2009 at 12:42 PM, herbie <4whi...@o2.co.uk> wrote:
>
>
> So will this :
> query = Foo.all().filter("property_x >" 50).order("property_x") .order
> ("-timestamp")
> results = query.fetch(200)
>
> ..get the latest entities where property_x > 50 ? Or will it get the
> 200 properties
So will this :
query = Foo.all().filter("property_x >" 50).order("property_x") .order
("-timestamp")
results = query.fetch(200)
..get the latest entities where property_x > 50 ? Or will it get the
200 properties with the largest 'property_x' which are then ordered
by 'timestamp' ? A subtle b
Yes, that is what it means. I forgot about that restriction.
I see what you mean about changing 'x' values. Perhaps consider
keeping two counts - a running sum and a running count (of the # of x
properties). If a user modifies an 'x' value, you can adjust the sum
up or down accordingly.
On Ju
I tried your query below but I get "BadArgumentError: First ordering
property must be the same as inequality filter property, if specified
for this query;"
Does this mean I have to order on 'x' first, then order on 'date'?
Will this still return the latest 200 of all entities with x > 50 if
I cal
I should clarify, I'm not saying move the 1000-entity fetch to the
write process, but instead keep a running total of sum and count that
you can increment and use to calculate the average, rather than having
to fetch entities. This doesn't solve the use case of "average of
last x entities", thoug
You could accomplish this task like so:
xlist = []
query = Foo.all().filter("property_x >" 50).order("-timestamp")
for q in query:
xlist.append(q.property_x)
avg = sum(xlist) / len(xlist)
What Nick is saying, I think, is that fetching 1000 entities is going
to be very resource-intensive, so a
Ok. Say I have many (>1000) Model entities with two properties 'x'
and 'date'.What is the most efficient query to fetch say the
latest 200 entities where x > 50. I don't care what their 'date's
are as long as I get the latest and x > 50
Thanks again for your help.
On Jun 22, 4:11 pm, "N
Consider precalculating this data and storing it against another entity.
This will save a lot of work on requests.
-Nick Johnson
On Mon, Jun 22, 2009 at 3:55 PM, herbie <4whi...@o2.co.uk> wrote:
>
> No the users won't need to read 1000 entities, but I want to calculate
> the average of a proper
No the users won't need to read 1000 entities, but I want to calculate
the average of a property from the latest 1000 entities.
On Jun 22, 3:30 pm, "Nick Johnson (Google)"
wrote:
> Correct. Are you sure you need 1000 entities, though? Your users probably
> won't read through all 1000.
>
> -Nic
Correct. Are you sure you need 1000 entities, though? Your users probably
won't read through all 1000.
-Nick Johnson
On Mon, Jun 22, 2009 at 3:23 PM, herbie <4whi...@o2.co.uk> wrote:
>
>
> So to be sure to get the latest 1000 entities I should add a datetime
> property to my entitie model and fi
So to be sure to get the latest 1000 entities I should add a datetime
property to my entitie model and filter and sort on that?
On Jun 22, 1:42 pm, herbie <4whi...@o2.co.uk> wrote:
> I know that if there are more than 1000 entities that match a query,
> then only 1000 will be return by fetch(
Hi herbie,
The first 1000 results of a query are the ones returned. If you do not
specify a sort order, entities are returned sorted by their keys.
-Nick Johnson
On Mon, Jun 22, 2009 at 1:42 PM, herbie <4whi...@o2.co.uk> wrote:
>
> I know that if there are more than 1000 entities that match a q
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