I don't have much experience with dealing with databases that have more than a few hundred records. But the other day I really got to wondering about how it is that with a database of more than 700 million records, when I enter my username and password into facebook I am greeted by the homepage in about less than a second with all my other information (news feeds and so on) displayed on this next page.
How exactly can the information I've entered be verified against so many records in such little time. I doubt facebook releases information like this so it's most likely going to be speculation on how they actually do it, but any ideas anyone?