1. 1 ACCTG 6910 Building Enterprise & Business Intelligence Systems (e.bis) Dimensional Modeling I Olivia R. Liu Sheng, Ph.D. Emma Eccles Jones Presidential Chair of Business

2. 2 Technical Architecture Design Product Selection & Installation End-User Application Specification End-User Application Development The Business Dimensional Lifecycle Project Planning Business Requirement Definition Business Requirement Definition Deployment Maintenance and Growth Project Management Dimensional Modeling Physical Design Data Staging Design & Development

3. 3 Outline Table structure, types, characteristics and terminology Design steps Dimensional models with varying types of fact and dimension tables

4. 4 Introduction to Dimensional Modeling A logical data warehouse design technique Objectives of Dimensional Modeling: –Intuitive: easy to understand and query –High performance OLAP

5. 5 Anatomy of Dimensional Models Facts or Fact Tables –Key – uniquely identifies a record –Attributes Dimensions or Dimension Tables –Keys –Attributes Connections –Between dimensions and facts –Cardinality: mostly one to many

6. 6 Fact and Dimension Tables There are two types of tables in dimensional models: –Fact table: attributes in fact tables are measurements for analysis or main contents in reports. –Dimension table: attributes in dimension tables are constraints for the measurements or headers in reports. Dimensions Facts

7. 7 Fact and Dimension Fact table Dimension tables

8. 8 Facts and Dimensions How to identify facts and dimensions? –Top-down approach (Requirements Analysis): Report Sales in terms of – total amt, total qty or avg. price Report Sales by PRODUCT name and/or category name Report Sales by CUSTOMER name, city and/or or state Report using a combination of the measures and constraints –Bottom-up approach (Select from meta data of data sources) Characteristics of fact and dimension attributes

9. 9 Facts and Dimensions CriteriaFact AttributesDimension Attributes PurposeMeasurements for reporting or analysis Constraints or qualifiers for the measurements Data typeAdditive or semi-additive quantitative data Textual, descriptive SizeLarger number of recordsSmaller number of records Reporting useMain report contentsRow or report headers ExamplesMeasurements for salesAbout time, people, departments, objects, geographic units