In most cases, the complete comparison method described just above takes less time than just loading the data into a database and constructing the indexes, without having even started comparing anything.

Ah! Someone who understands to pick up the baton :)

As (seemingly) the lone voice making that exact point for the 10+ years, it's good to see.

Warning: be careful with your examples. erix has had the delightful habit of proving me wrong if my 'slow DB' examples are poorly chosen.

Also be(a)ware of Oracle's latest hardware/DB monsters. Not that I would ever use anything that company makes -- assuming I had any influence -- but if you can afford it (the lock-in as much as the price), Oracle's latest hardware/in-memory DB is capable of some pretty amazing performance as they recently demonstrated to an old client of mine.