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A comment on Show HN: Valhalla, an open source routing engine. Parent comment

Re:Show HN: Valhalla, an open source routing engine by zzleeper on Friday June 05, 2015 @02:21AM (#9664131)
The problem is I have 5MM "users" through several years and I want to compute their distance to a set of points that change through time, so I do care a lot about speed.

Computing the geodesic distances was slow but not that slow because I used a variation of R* with some caching on top, but I still had to compute around 5MM distances or so.

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Re:Show HN: Valhalla, an open source routing engine by imaginenore on Friday June 05, 2015 @06:30AM (#9664745)
How can computing geodesic distances be slow? Isn't it rather trivial math? I'm pretty sure 5 million of them can be calculated in a few seconds on my laptop. And it can be offloaded to the client.

Whereas route calculation can't be easily offloaded.

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