Pagination and timeouts

[Tom van den Berge <to...@drillster.com>]

I have a table with some 1M rows, and I would like to get the partition key
of each row. Using the java driver (2.1.9), I'm executing the query

select distinct key from table;

The result set is paginated automatically. My C* cluster has two
datacenters, and when I run this query using consistency level LOCAL_ONE,
it starts returning results (page by page) as expected. But after some
time, it will give a ReadTimeoutException. This happens anywhere between 30
seconds and a few minutes.
The java driver's read timeout is set to 500000 ms, and the cluster's
read_request_timeout_in_ms is 300000 ms.

I'm wondering what is causing this timeout?

What is also not clear to me is whether the driver and server timeout apply
to a single page, or to the entire query?

Thanks,
Tom