I remember when Netezza were brought in to trial their database for a VERY large dataset (I cannot name names unfortunately). A typical table had over 30 million rows!
Running a constrained SQL query on a beefed up DB2 database took up to a minute, the same query, the same data, on a Netezza box, took seconds to complete!
My jaw dropped when I saw this response, and I was surprised that it was not bought by the client. Furthermore, I loved the fact that I didn't need to constrain myself to indexed fields only!
</Not a Netezza employee or have a vested interest, but have worked along side them in the past, and LOVED their offering!>