[OSM-dev] OSM API Performance (Was: OSM Database Infrastructure)

[Robert (Jamie) Munro]

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Tom Hughes wrote:
| In message <20080119234103.GA1098 at alta.metacarta.com>
|           Christopher Schmidt <crschmidt at metacarta.com> wrote:
|
|> In the past, I think that we had talked about the fact that the /map
|> request is resource intensive compared to most of the other ruby calls,
|> and that some of it is memory + CPU intensive and might be a small chunk
|> worth improving performance in. Given that sometimes the requests are
|> returning reasonably quickly, this may be premature optimization if al
|> lthe wait time is waiting for an available rails daemon.
|
| It is not especially CPU intensive. It is I/O and memory intensive
| but there isn't much we can do about that (well there is, but it
| probably isn't an answer people will want to hear).

I guess it is only the map call that is a problem. If that is the case,
as this is a read-only call that needs not authentication or other rails
related input, could we rewrite it in a more efficient language that is
capable of streaming the data directly and use apache rewrites or
similar to serve them?

I think we should also offer 2 versions of the map query - the one that
we already have, that completes all the ways outside the box, and
another that just indicates which ways are incomplete, but takes less
resources to run, and therefore runs quicker. Ideally, there would also
be an option to add one node for any ways that go off the east or south
of the box so that if you download 2 adjoining areas, you will get all
the data once and once only.

Robert (Jamie) Munro
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