Best practice to query large number of ndb entities from datastore

Question

I have run into an interesting limit with the App Engine datastore. I am creating a handler to help us analyze some usage data on one of our production servers. To perform

Answer 1

Large processing like this should not be done in a user request, which has a 60s time limit. Instead, it should be done in a context that supports long-running requests. The task queue supports requests up to 10 minutes, and (I believe) normal memory restraints (F1 instances, the default, have 128MB of memory). For even higher limits (no request timeout, 1GB+ of memory), use backends.

Here's something to try: set up a URL that, when accessed, fires off a task queue task. It returns a web page that polls every ~5s to another URL that responds with true/false if the task queue task has been completed yet. The task queue processes the data, which can take some 10s of seconds, and saves the result to the datastore either as the computed data or a rendered web page. Once the initial page detects that it has completed, the user is redirected to the page, which fetches the now computed results from the datastore.