Comparison of Data Warehouse Methodologies

For the MD approach, the multidimensional or star schema data model is easy to understand by the business community. The data model is generally less complex and resembles the way many business community members think about their data—that is, they think in terms of multiple dimensions, for example, “Give me all the sales revenues for each store, in each city and state, by market segment over the last two months.” Thus, it is also easier to construct by the IT data modelers. However, given the complexity of an enterprise view of the data as you go from data mart implementation to data mart implementation, retrofitting is significantly harder to accomplish for this architecture. That is why the CIF architecture places the star schema designs in the data marts only—never in the data warehouse itself. Functionality The multidimensional architecture provides an ideal environment for relationally oriented multidimensional processing, ensuring good performance for complex “slice and dice,” drill-up, -down, and -around queries. All dimensions are equivalent to each other, meaning that all queries within the bounds of the star schema are processed with roughly the same symmetry. We recommend that it be used for the majority of CIF data mart implementations. But do remember that multidimensional modeling does not easily accommodate alternate methods of analysis such as data mining and statistical analysis. The CIF uses a data model that is based on an ERD methodology that supports the business rules of the enterprise. This type of model is also easily enhanced or appended if need be. Attributes are placed in the data model based on their inherent properties rather than specific application requirements. This is an important differentiator in the BI world because it means that the data warehouse is positioned to support any and all forms of strategic data analyses, not just multidimensional ones. Data mining, statistical analysis, and ad hoc or exploration functionalities are supported as well as the multidimensional ones. Ongoing Maintenance There is an old adage: “Pay me now or pay me later.” For this final discussion, that adage should be expanded to include: “But it will cost you a lot more if you pay me later.” By now, you realize that the whole purpose behind the CIF is to stop the high costs of later constructions, adjustments, retrofits, and suboptimal accommodations to your BI environment. It may cost you a bit more up front, in terms of making the effort to capture an enterprise view of your company’s data for your first or second BI implementation. However, BI environments build upon the past iterations and will take years to complete, if it’s ever finished. Just as a sound foundation for a house takes forethought and is absolutely necessary for the longevity of the structure, regardless of the