[postgis-users] Is postgis the right tool for this?

[Gregory S. Williamson]

Well, on the face of it this seems like postGIS could well handle it, depending on server, expected load, etc.

If you data is is in lat/long you can load it as such with an appropriate SRID (4326 springs to mind) but in order to get a distance in miles you'll have to cast that data into a projection that does feet/meters/miles (with whatver conversions are needed) ... this projection obviously differs if you are area around Fairbanks Alaska vs Florida. There are people on this list who can probably offer much better advice than I on this (I more of a DBA and less of a GIS type).

Roads are doable but you either have to pay a fair chunk of change for prepared datasets or you can use TIGER data from the US Census department,which tends to be a bit less accurate and perhaps a bit older, but is often good enough for causal use and are at least free. But they come in a format that requires massaging to get into postgres -- there have been posts on this in the past so searching the archives might be useful.

HTH,

Greg Williamson
DBA
GlobeXplorer LLC



-----Original Message-----
From:	postgis-users-bounces at postgis.refractions.net on behalf of snacktime
Sent:	Mon 6/5/2006 10:33 PM
To:	postgis-users at postgis.refractions.net
Cc:	
Subject:	[postgis-users] Is postgis the right tool for this?

I'm very new to GIS, but we use postgresql extensively so postgis
naturally came to mind when we landed this project.

We need to create a nearest neighbor search feature.  The search will
be for doctors within a certain radius measured by miles.  The
database of doctors is right at 1 million.  Whether the search wll be
within the radius of a specific street address or just a city is
unknown at this time.  If compiling a complete US street address
database with latitude and longitude isn't too much work we will do
that, but if that proves unworkable we will probably just fall back to
searching the radius of a city.

I've read over some of the postgis documentation, and it appears that
the Distance function would do what we need.  I also saw a post on
this list that suggested postgis might not be well suited to what we
need, so I'm looking for some confirmation on if postgis is or is not
a suitable tool for our situation.
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