[OSM-dev] Best and FASTEST Spatial DB for only calculating points near to X?
ander.pijoan at deusto.es
Fri Dec 14 20:42:20 GMT 2012
2012/12/14 Martin Schafran <martin at ampelmeter.com>
> use ssd,
> cluster nodes on spatial index,
> perform vacuum
> and show us your query.
Thanks a lot for the advice. The query as I previously mentioned it would
be as simple as a "SELECT * FROM db WHERE X=X AND DISTANCE<5km". There
wouldn't be more type of queries.
2012/12/14 Christian Vetter <veaac.fdirct at gmail.com>
> If the only thing you are interested in is asking for the amount of points
> within a given radius, I would strongly advise not to use a database, but
> quickly implement a dedicated data structure for that. That can usually be
> an order of magnitude faster than a general purpose database.
> E.g. consider a simple KD-Tree :
> When doing you query you can simply stop recursion if the current block is
> completely within the given circle.
> You can implement a KD-Tree in a really lightweight manner, completely
> implicitly. Just storing the coordinates, the KD-Tree structure is encoded
> in the ordering of them. You can have a look at an example : Have a look
> at the function NearNeighbors, it could easily be modified to count the
> amount of points instead of returning them.
> The only reason I could think of for using a database is, that you have to
> handle much more data than fits into memory. However, even in that case a
> specialized data structure should perform better - it's only more effort to
> implement :-)
> Best regards,
> Christian Vetter
> : http://en.wikipedia.org/wiki/K-d_tree
Hmmm, didn't thought about this. I don't know about K-D trees but I will
search for information about it. Thank you very much.
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