Microsoft® SQL Server 2012 Unleashed

An Analytics Design Methodology

A data warehouse can be built from the top down or from the bottom up. To build a top-down warehouse, you need to form a complete picture or logical data model for the entire organization (or all the subsystems within the scope of the project, such as all financial systems). In contrast, building a warehouse from the bottom up takes a much more departmental or specific business-area focus (for example, a sales order system only). This breaks the task of modeling the data into more manageable chunks. Such a departmental approach produces data marts that are potentially subsets of the overall data warehouse. The bottom-up approach can simplify implementation. It helps get departmental or business-area information ...