[OSM-dev] Alternative PostgreSQL Schema
tom at compton.nu
Wed Oct 24 15:16:28 BST 2007
In message <471F505C.1040207 at bretth.com>
Brett Henderson <brett at bretth.com> wrote:
> Patrick Weber wrote:
>> geo spatial indexing sounds great. how far could one then go with
>> spatial queries as well?
> My knowledge of the geo-spatial stuff is very limited at the moment so
> no idea :-) All I know is that for some reason a point can't be indexed
> directly but some trickery with the "circle" function allows you to work
> around that. In theory it should provide something similar to the
> existing quad tiles in MySQL but I have no idea if that's how it will
> work out. It might also be possible to add some geo-spatial information
> to ways but that might be moving beyond the realms of the current OSM
> data model.
The point is that you don't actually need (and probably don't want) to
create a single field of type point. You just want to create a 2D index
over the latitude and longitude columns:
CREATE INDEX node_latlon ON node USING gist (latitude, longitude)
I think that's the right syntax anyway...
That will sufficient to resolve simple queries along the lines of:
SELECT * FROM node WHERE latitude BETWEEN ... AND longitude BETWEEN ...
Tom Hughes (tom at compton.nu)
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