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From pablo platt <pablo.pl...@gmail.com>
Subject Re: using couchdb for 100GB geodata from openstreetmap
Date Sun, 22 Mar 2009 22:45:02 GMT
On Mon, Mar 23, 2009 at 12:32 AM, Volker Mische <volker.mische@gmail.com>wrote:

> Hi,
>
> I'll only reply to the GeoCouch bit:
>
> > I've read about geocouch -
> >
> http://vmx.cx/cgi-bin/blog/index.cgi/geocouch-geospatial-queries-with-couchdb:2008-10-26:en,CouchDB,Python,geo
> > and my question is if a geo aware couchdb can be built without any python
> > and SpatiaLite code?
> >
> > If I want to be able to make proximity searches - find banks in 3km range
> > from st some-street
> > do I need to create some kind of index docs for the views?
>
> The problem is that proximity searches are kind of dynamic. CouchDB
> views are like precomputed result-sets, but you can't precompute all
> possible values, as the center of the search could possibly be anywhere.
> Therefore you need something that makes such dynamic requests possible.
>
> Pure CouchDB could be used if you constrain your searches. You would
> need to restrict to things like, a certain number for the center of
> searches, only a fixed number of radii, and a fixed number of location
> types (like banks, restaurants etc).
>
> Cheers,
>   Volker
>

I've asked on the #couchdb channel and got the same answer.

The 'Name Finder' on OSM http://wiki.openstreetmap.org/index.php/Name_finder
divides the map to region and add a field to each element(place) indicating
what region it belongs.
When you make a search "banks near someRoad" it find in which region
someRoad is and find all the banks in that road.
So you are limited to predefined distances but the above design will work in
couchdb as well.
There is an assumption that they used this design because they used MySQL
but I can't verify that.

My question is if arbitrary distances are not a requirement of my app, is it
better to use couchdb for storing the geodata
or is it better to use a spatial db like postGIS in any case.

Thanks

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