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Patch to add useful distance
Posted by: Jesse Dailey
Date: May 04, 2008 06:38PM

After reading the OpenGIS for SQL specifications, it's apparent that there is a layer of Spatial Representation control that is still missing from MySQL.

This makes the Distance functions as implemented not very useful for what most people use GIS for: latitude and longitude on the earth's surface.

In the meantime, I have a patch that adds 2 functions: earth_distance_miles() and earth_distance_km() to the wl1326 branch.

To find the nearest X rows, on a database with 600k rows with a POINT column:
earth_distance_*() takes 3.04 seconds.
distance() takes 2.78 seconds.

If anyone would like a copy of the patch you can find it here: http://www.twintechs.com/blog/?p=15
UPDATE: link fixed, was 404. :(

Note, this assumes you are storing your POINT as POINT(latitude longitude). Which I understand is not how people expect this to be at some point in the future.



Edited 3 time(s). Last edit at 05/22/2008 05:42AM by Jesse Dailey.

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