Correct datatype for latitude and longitude? (in activerecord)

Question

Should I store latitude and longitude as strings or floats (or something else)?

(I'm using activerecord / ruby on rails, if that matters).

Answer 1

I would suggest using floats, although it doesn't really make that much of a difference. Floats are easier to do calculations on if you ever desire that in the future.

Answer 2

If you need to do more complex geographical calculations, you can investigate PostGIS for Postgresql or MySQL Spatial Extensions for MySQL. Otherwise, a float (double precision might be a good idea) should work.

Edit: It looks like the GeoRuby library includes a Rails extension for working with the spatial/GIS extensions for both of the aforementioned databases.

Answer 3

Generally you want Lat/Long stored in the largest float type you have. At some latitudes (eg: near the equator) very small changes in longitude can equate to large differences in terms of surface distance.

I suppose if it is a field which you won't ever want to do any math on, you could use a string. I'd avoid that though.

Answer 4

If you're not using a spatially-enabled database, Google Maps recommends using floats of size (10,6). That gives you 6 digits after the decimal - if you want more precision, you can adjust accordingly.