A multidimensional model provides a logical view of an enterprise by showing the main entities and relationships between them without being tied to physical database tables. It includes dimensions with hierarchies, attributes, and facts along with their relationships. An example model shows dimensions for time and geography with attributes like year, quarter, and country. Facts represent measurable data that can be aggregated, and attributes are additional data items used for qualifying or summarizing reports. Relationships between attributes can be one-to-one, one-to-many, many-to-many, or many-to-one. Hierarchies allow ordering dimensions like time periods.

1. Multidimensional Modeling
MIS 497

2. What is multidimensional model?
 Logical view of the enterprise
 Shows main entities of the enterprise
business and relationships between them
 Not tied to a physical database and tables
 Not E-R diagram

3. Model Components
 Dimensions (Hierarchies in MSTR 7)
 Attributes
 Facts
 Relationships

4. Multidimensional Data Model
Example
Time
Year
Quarter
Month
Day
Geography
Country
Region
City
Store
Products
Division
Department
Category
Item
Store Manager

5. Attributes
 Attributes are abstract items with
business relevance that are
created for convenient
qualification or summarization of
data on a report.
 Attribute can also be defined as
column headings on a report that
are not a calculation

6. Attribute relationships
 One to One
– Each customer has only one SSN.
 One to Many
– Each customer can have several addresses.
 Many to Many
– Each customer can buy many items, an item can be
purchased by many customers (item means SKU, not
the same physical object).
 Many to One
– Several phone numbers can belong to one store, and
one store only.

7. Attribute relationships
 Out of all relationships, Many to Many is the trickiest one.
If not modeled carefully, M;N can lead to double-counting
and other unhappy consequences.
 Practical ways of dealing with M;N relationships:
– Create a relationship table
– Create a compound key
» Not advisable, but sometimes necessary

8. Hierarchies (Dimensions)
 Hierarchies have the same meaning
as Dimensions in MicroStrategy 7.
 Hierarchies are based on
relationships between Attributes.
They allow end users to define and
order groups of Attributes for display
and browsing purposes.
Time
Year
Quarter
Month
Day

9. Facts
 Data columns (usually numeric) that can be used to perform
calculations needed to answer business questions.
 Facts are stored in Fact Tables or Base Tables
 Facts can be aggregated on different levels:
Aggregated on
Region level
Aggregated on
Country level

10. Facts (continued)
 Same facts can be represented by different column name in the DW
due to various historical and design reasons.
 In the example below the same fact has two different names: SALES
and DOLLAR_SALES
 Facts are cross-dimensional, not limited to one dimension
only. In the example above, the same fact crosses two
dimensions: Geography and Time.

11. Facts (continued)
 Facts are used to create metrics.
 Metrics - business measurements (i.e. Dollar Sales, Units Sold, Gross
Margin and etc.) used by businesses to analyze and report their
performance.
 Metrics are usually a fact that has a mathematical function applied to it
(sum, average, max, min and etc.)
 More on metrics in a separate presentation

12. What to read for more information:
 MicroStrategy 7 Project designer guide.
 Have a good look at VMALL Data Model
– Identify attributes, hierarchies and facts – you’ll
need them for the Workshop.