Building a Q&A platform that is scalable.

Question

I am planning to use open source, SQL/NoSQL? MVC? CQRS? caching? hadoop? Bigtable? S3? By scalable I mean supporting +1M users

This is a social-change venture (not-for-profit), including geo-location and social networking features.

Answer 1

http://blog.stackoverflow.com/2008/09/what-was-stack-overflow-built-with/

Answer 2

depending on your scalability goals, you may start with Mysql and end up with noSQL systems (such as MongoDB, cassandra etc).. MVC is good anyway for layer separation CQRS is interesting especially to scale up reads vs writes independently, but requires a good thinking about the UI Caching is a must IMO, Varnish, memcached and memcacheDB (persistent)