Geocoding and reverse geocoding using the GeoNames datasets
In this recipe, you will write two PL/PostgreSQL PostGIS functions that will let you perform geocoding and reverse geocoding using the GeoNames datasets.
GeoNames is a database of place names in the world, containing over 8 million records that are available for download free of charge. For the purpose of this recipe, you will download a part of the database, load it in PostGIS, and then use it within two functions to perform geocoding and reverse geocoding. Geocoding is the process of finding coordinates from geographical data, such as an address or a place name, while reverse geocoding is the process of finding geographical data, such as an address or place name, from its coordinates.
You are going to write the two functions using PL/pgSQL, which adds on top of the PostgreSQL SQL commands the ability to tie more commands and queries together, a bunch of control structures, cursors, error management, and other goodness.
