[mister_goo]

SpatiaLite is a great extension for spatial functions, it is very useful for implementing location-based services. And I like the idea of extending SQLite just for the simplicity of file base DB.

A slightly related problem I encountered several times is reverse geocoding: given a point, a map, which polygon the point is in? I figured out that the problem is solvable via rasterization and run-length-encoding, which doesn't need a spatial library, and works efficiently with any SQL DBs without GIS/spatial extensions. I created a website (https://reverse-geocoding.com/) to demonstrate the idea, which has a GPS-to-country DB in SQLite format.