As someone that's worked on a few decent sized projects (2-3 million pageviews / day), I can say that a normalized database is a complete nightmare to try to work with. It just doesn't scale. I'm not sure what constitutes a "huge" data warehouse, however, if you're running a SELECT with a where clause that triggers a table scan against more than a million rows, yeah, it'll take a while, no matter if you're selecting against an integer or a char field.