13 1 Chapter 13 The Data Warehouse Database Systems: Design, Implementation, and Management, Seventh Edition, Rob and Coronel

13 2 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Relational OLAP (continued)

13 3 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Multidimensional OLAP Extends OLAP functionality to multidimensional database management systems (MDBMSs) –MDBMS end users visualize stored data as a 3D cube-a data cube –Data cubes can grow to n number of dimensions, becoming hypercubes –To speed access, data cubes are held in memory in a cube cache

13 4 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Multidimensional OLAP (continued)

13 5 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Relational vs. Multidimensional OLAP

13 6 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Star Schemas Data modeling technique used to map multidimensional decision support data into relational database Creates near equivalent of multidimensional database schema from existing relational database Yield an easily implemented model for multidimensional data analysis, while still preserving relational structures on which operational database is built Has four components: facts, dimensions, attributes, and attribute hierarchies

13 7 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Facts Numeric measurements (values) that represent specific business aspect or activity –Normally stored in fact table that is center of star schema Fact table contains facts that are linked through their dimensions Metrics are facts computed or derived at run time

13 8 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Dimensions

13 9 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attributes Used to search, filter, or classify facts Dimensions provide descriptive characteristics about the facts through their attributes

13 10 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attributes (continued)

13 11 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attributes (continued)

13 12 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attributes (continued)

13 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attributes (continued)

13 14 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attribute Hierarchies Provides top-down data organization Provides capability to perform drill-down and roll-up searches in a data warehouse

13 15 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attribute Hierarchies (continued)

13 16 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Attribute Hierarchies (continued)

13 17 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Star Schema Representation Each dimension record is related to thousands of fact records Facilitates data retrieval functions

13 18 Database Systems: Design, Implementation, & Management, 7 th Edition, Rob & Coronel Star Schema Representation (continued)