How to scale a geolocation web application

I am building a geolocation web application and I am really in the blur how I am going the handle the geolocation.

Briefly my app lets you create adverts on a specific city. The idea is to avoid the basic form with the city name, zipcode, country and just have an autocomplete field based on the city name.

I have a few idea how to handle that but I am not sure which one is the best. There first one is to get a world cities database from maxmind (3M cities) and sele开发者_如何学编程ct from my database.

The other one is to use YQL and the geo API from yahoo...

I really don't know what is the best practice for this kind of app...

Greg

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I have done some geolocation using the geokit plugin and gem. It works well with multiple geolocation providers (google and yahoo).

https://github.com/andre/geokit-gem