Hi Bruce,
One option might be the Channel API, depending on what your client
is written in. I assume you're not sending that many results to a
browser though, so it might not work for you.
http://code.google.com/appengine/docs/python/channel/
Another option would be for your client to submit the request, then
you could kick off a background job (using tasks) to write the result
set to the blobstore, and once complete the client could download the
blob and process it. You're client would need to periodically check
with the server to know when the query is complete.
http://code.google.com/appengine/docs/python/blobstore/overview.html#Writing_Files_to_the_Blobstore
And, the most basic solution to implement from the server side would
be to use cursors. If you can adjust the client to download chunks at
a time, this would probably be the easiest.
http://code.google.com/appengine/docs/python/datastore/queries.html#Query_Cursors
Robert
On Thu, Jun 9, 2011 at 06:06, Bruce Aloe <brucea...@gmail.com> wrote:
> Hello,
>
> I store quite a lot of data (e.g 10 million) tuples (rows) in my
> Person kind (table) at GAE datastore. Now i want to query the Person
> kind from my web application. For example my web application sends a
> query (e.g select * from Person where height < 2) through a http
> request to my server (python code) and the server gets the query and
> run it in order to generate the result tuples. For this query (select
> * from Person where height < 2), the server will generate quite big
> dataset (tuples) back since not many people are taller than 2m. Due to
> the generated result tuples are too big, i can not send the whole
> result tuples in one time through a http response to my web
> application. Therefore, i use cursor with the query and each time
> generate a partial result tuples (e.g 10000) from the total result
> tuples generated by running the query and try to return the 10000
> result tuples each time through a http response. As you might realize,
> i send just one http request with a query to my server and want my
> server to send many http responses to my web application and each
> response carries 10000 result tuples to my web application.
>
> My question is: How can my server sends many http responses back to my
> web appilcation for a http request sending from my web application?
>
> Thank you very much!
>
> Bruce
>
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