We have long been concerned that the data warehousing market is treated as if it was homogeneous, with all vendors potentially tackling all warehousing issues. This is very far from the truth: for example, some products are specifically focused on supporting analytics while others are targeted at enterprise data warehouses. Similarly, some suppliers target the low end of the market, measured in gigabytes or perhaps a few terabytes, while others concentrate on implementations with tens or hundreds of terabytes, or even petabytes. Trying to compare all of these offerings within a single paradigm makes no sense. We have therefore elected to break the market down in terms of both functionality (analytic marts and warehouses on the one hand, and enterprise data warehouses on the other) and, in the case of the former: scale (small, medium and large). We have not distinguished in scale terms across enterprise data warehouses because the two tend to go hand in hand. Each of these four sub-market examinations is available as an individual paper in its own right, but each refers back to this one as its foundation document in which we discuss market requirements and vendors.