> Why does Google need to keep all of this data, when they could just classify (cluster) people based on their searches, and keep only that information? That a

> Why does Google need to keep all of this data, when they could just classify (cluster) people based on their searches, and keep only that information? That assumes you can take a pre-generated cluster and add information to it without having to recompute with all the original information. It also assumes there's nothing you can do with personal search histories to either target adverts more effectively or add features, which would absolutely amaze me.