These sort of questions have resulted in the traditional web setup you see today with a database backend for storage. Any reasonably large site will (relativel

These sort of questions have resulted in the traditional web setup you see today with a database backend for storage. Any reasonably large site will (relatively) quickly exhaust RAM, especially if the same server is handling the requests. Plus, traditionally there are large sets of data that needs to be searchable, hence the desirability of putting it in a database. So instead of actually having things in memory, people now use something like memcache to reasonably simulate that for performance.