Storing Lat Lng values in MySQL using Spatial Point Type

Question

Tech used: MySQL 5.1 and PHP 5.3

I am just designing a new database for a site I am writing. I am looking at the best way of now storing Lat and Lng values.

Answer 1

If you can affor placing some extra code into your backend, use Geohash.

It encodes a coordinate into a string in a way that prefixes denote a broader area. The longer your string is, the more precision you have.

And it has bindings for many languages.

http://en.wikipedia.org/wiki/Geohash https://www.elastic.co/guide/en/elasticsearch/guide/current/geohashes.html

Answer 2

I think you should always use the highest level abstraction easily available. If your data is geospatial, then use geospatial objects.

But be careful. Mysql is the worst geospatial database there is. Its OK for points but all its polygon functions are completely broken - they change the polygon to its bounding rectangle and then do the answer on that.

The worst example that hit me is that if you have a polygon representing Japan and you ask what places are in Japan, Vladivostok gets into the list!

Oracle and PostGIS don't have this problem. I expect MSSQL doesn't and any Java database using JTS as its engine doesn't. Geospatial Good. MySQL Geospatial Bad.

Just read here How do you use MySQL spatial queries to find all records in X radius? that its fixed in 5.6.1.

Hoorah!

Answer 3

It's a good thing, because then you get to use spatial indexes on your queries. Limit to a bounding box, for example, to limit how many rows to compare against.

Answer 4

Mysql GIS yagni:

If you have no experience with GIS, learning spatial extensions is practically like learning a new database, plus a little math, and a lot of acronyms. Maps, projections, srids, formats... Do you have to learn all that to calculate distances between points given a certain lat/long: probably not, will you be integrating 3rd party GIS data or working with anything more complex than points, what coordinate system will you be using?

Going back to yagni: do things as simple as posible, in this case implement your code in php or with simple SQL. Once you reach a barrier and decide you need spatial, read up on GIS system, coordinate systems, projects, and conventions.

By then, you will probably want PostGIS.