On Fri, Dec 26, 2003 at 10:34:04PM -0600, Bruno Wolff III wrote: > On Fri, Dec 26, 2003 at 19:42:44 -0700, > Michael Fuhr <[EMAIL PROTECTED]> wrote: > > > > I have several databases with lat/lon coordinates and frequently make > > "show me all records within a certain distance of this point" queries. > > I wrote a haversine() function that uses the Haversine Formula to > > calculate the great circle distance between two points on a sphere > > (assuming the earth is a perfect sphere is accurate enough for my uses). > > Here's a web site with related info: > > The distance operator in contrib/earthdistance got changed to use > haversine instead of the naive formula in 7.3. In 7.4 it also provides > some functions that work with contrib/cube that allow for indexed > searches.
I'll have to take a closer look at contrib/earthdistance. I'm using the function I wrote for legacy reasons -- I had ported an application from another DBMS to PostgreSQL and wanted to make as few changes as possible, so I ported the haversine() function that I had already written. Incidentally, I see the following in README.earthdistance: A note on testing C extensions - it seems not enough to drop a function and re-create it - if I change a function, I have to stop and restart the backend for the new version to be seen. I guess it would be too messy to track which functions are added from a .so and do a dlclose when the last one is dropped. Maybe you've already figured it out, but LOAD should allow you to reload a .so file without having to restart the backend. http://www.postgresql.org/docs/current/static/sql-load.html -- Michael Fuhr http://www.fuhr.org/~mfuhr/ ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
