My first Publication Agile-Data-Warehouse-Design-eBook | Page 47

26 Chapter 1 Summary Data warehouses and operational systems are fundamentally different. They have radically different database requirements and should be modeled using very different techniques. Dimensional modeling is the appropriate technique for designing high-performance data warehouses because it produces simpler data models—star schemas—that are optimized for business process measurement, query performance and understandability. Star schemas record and describe the measureable events of business processes as fact tables and dimensions. These are not arbitrary denormalized data structures. Instead they represent the combination of the 7Ws (who, what, when, where, how many, why and how) that fully describe the details of each business event. In doing so, fact tables represents verbs, while the facts (measures) they contain and the dimensions they reference represent nouns. Dimensional modeling’s process-orientation supports agile development by creating database designs that can be delivered in star schema/business process increments. Even with the right database design techniques there are numerous analysis challenges in gathering detailed data warehousing requirements in a timely manner. Both data-driven and reporting-driven analysis are problematic, increasingly so, with DW/BI development becoming more proactive and taking place in parallel with agile operational application development. Iterative, incremental and collaborative data modeling techniques are agile alternatives to the traditional BI data requirements gathering. BEAM✲ is an agile data modeling method for engaging BI stakeholders in the design of their own dimensional data warehouses. BEAM✲ data stories use the 7Ws framework to discover, describe and document business events dimensionally. BEAM✲ modelers encourage collaboration by using simple modeling tools such as whiteboards and spreadsheets to create inclusive data models. BEAM✲ models use example data tables and alphanumeric short codes rather than ER data abstractions and graphical notation to improve stakeholder communication. These models are readily translated into star schemas. BEAM✲ is an ideal tool for modelstorming a dimensional data warehouse design.