[Maposmatic-dev] PostGIS help for MapOSMatic

[Thomas Petazzoni]

Hi Vincent, Jean-Christophe, Guilhem and Sébastien,

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I'm writing to you concerning a PostgreSQL/PostGIS request optimization
problem we have in MapOSMatic (http://www.maposmatic.org). The request
in question is the one that gives us the list of the streets and the
squares they intersect for a given city.

Currently, for a city like Toulouse, the request takes 4 minutes and 39
seconds, but our experiment show that it could be optimized down to 3.2
seconds. But we don't know exactly how to generalize our experiments of
optimization.

Inside of writing a long e-mail, I've written a detailed explanation of
the request, the problem and the analysis we've done so far at
http://wiki.maposmatic.org/doku.php?id=dev:request_optimization.

If you have the time, could you have a look and tell us what we are
doing wrong ? Solving this problem would probably allow us to limit the
load on the server and to generate maps for larger cities. Of course,
if you need details about the request or the environment, don't
hesitate.

Thanks a lot for your help,

Thomas
-- 
Thomas Petazzoni                         http://thomas.enix.org
Promouvoir et défendre le Logiciel Libre http://www.april.org
Logiciels Libres à Toulouse              http://www.toulibre.org

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