Well, say I am a programmer, and I find I can get most of what I need from the internet from Europe, North America, and Australia, for example. And, to keep th

Well, say I am a programmer, and I find I can get most of what I need from the internet from Europe, North America, and Australia, for example. And, to keep the pool small and focused I turn off all media sources (news, entertainment, etc.). The crawler would use white-lists to include obvious omissions. I wonder how small you could get the pool of indexed data and still get effective search results.