Web-framework+db with the widest scalability?

[Alec Taylor]

Disclosure: I have posted this on stackoverflow and comp.lang.python.

I am building a project requiring high performance and scalability, entailing:

• Role-based authentication with API-key licensing to access data of specific users
• API exposed with REST (XML, JSON), XMLRPC, JSONRPC and SOAP
• "Easily" configurable getters and setters to create APIs accessing the same data but with input/output in different schemas

A conservative estimate of the number of tables—often whose queries require joins—is: 20.

Which database type—e.g.: NoSQL or DBMS—key-value data store or object-relational database—e.g.: Redis or PostgreSQL—and web-framework—e.g. Django, Web2Py or Flask—would you recommend?

Thanks for all suggestions