I hear a lot of comparisons between between Teradata and Oracle Exadata.  There is a lot of marketing and hype about these big database vendors.  Martin Willcox wrote an interesting blog comparing the spin between Teradata and Oracle Exadata.  Martin talks about how Softbank switched from Teradata to Oracle Exadata and how Oracle is trumpeting this switch.  He also talks about a large number of customers switching from Oracle to Teradata.  Worth a quick read.