IBM Cognos Dynamic Cubes

Chapter 2. IBM Cognos Dynamic Cubes architecture 13

Figure 2-4 shows routing of a query to a summary table.

Figure 2-4 Routing of a query to a summary table

2.1.2 Modeling dynamic cubes

Cognos Cube Designer is used to model dynamic cubes on star or snowflake data

warehouses that are stored in a relational database. Cognos Cube Designer analyzes a cube

model as it is being constructed to ensure the underlying data warehouse is truly a star or

snowflake, and raises exceptions if it recognizes relationships in the data that contradict

constraints of either data topology.

A Cognos Cube Designer project can contain one or more namespaces. A namespace can

contain a collection of dimension definitions which can then be used to model one or more

cubes within the namespace. A dynamic cube is associated with a single fact table in the

underlying data warehouse and contains dimensions defined either in the encompassing

namespace, or within the cube itself, that is, dimensions which are specific to a particular

cube.

Time

Ye a r

Quarter

Month

Sto r e s

Country

St a t e

City

St o r e

Measur es

Cost

Year Quarter Coun try Stat e Cit y Cos t

Year Quarter Month Country Cost

Year Country State Cost

Summary1

Summary2

Summary3

Dimensions

Month Store Cost

Fact Table

Data Re qu e ste d Wit ho ut Su mmaries Wit h Summa ries

Co s t by Ye ar , St at e SUM( Fa ct.Cost)

GRO UP BY Year, S tore

SUM( Su mmary3 .Cost)

GROUP BY Ye ar , S tore

Cost by Quarte r, C ountry SUM( Fa ct.Cost)

GRO UP BY Quarter , Coun try

SUM( Su mmary2 .Cost)

GROUP BY Quart er, Coun try

Co s t by Qu ar te r , St at e SUM( Fa ct. Co s t)

GRO UP BY Quarter , S ta te

SUM( Su mmary1 .Cost)

GROUP BY Quarter, S ta te

14 IBM Cognos Dynamic Cubes

Figure 2-5 shows metadata objects in Cognos Cube Designer.

Figure 2-5 Metadata objects in Cognos Cube Designer

Another possibility in Cognos Cube Designer is to model virtual cubes, which represent a

merging of the members and data of two other cubes, either of which may be a Dynamic

Cube or another virtual cube. With virtual cubes, users can analyze data that encompasses

multiple fact tables, such as sales and inventory data.

Cognos Dynamic Cubes supports the following features, all of which are modeled in the

Cognos Cube Designer:

򐂰 Dimensions

򐂰 Multiple hierarchies per dimension

򐂰 Level attributes

򐂰 Parent-child (recursive) hierarchies

򐂰 Time hierarchies, including automatic creation of relative time members

򐂰 Calculated (dimensional) members and measures

򐂰 Member security

򐂰 Aggregate cubes

򐂰 Virtual cubes

Cognos Cube Designer also provides a member browser, which can be used to validate the

structure of a hierarchy as it is being modeled.

Chapter 2. IBM Cognos Dynamic Cubes architecture 15

Figure 2-6 shows viewing members in the Cognos Cube Designer member browser.

Figure 2-6 Viewing members in the Cognos Cube Designer member browser

Cognos Cube Designer also allows a modeler to validate all or part of a cube model to identify

modeling problems as they occur. Figure 2-7 shows how to validate an object.

Figure 2-7 Validating an object in the Cognos Cube Designer

Figure 2-8 shows a Cognos Cube Designer validation error message.

Figure 2-8 Cognos Cube Designer validation error message

After a cube is modeled in Cognos Cube Designer, the modeler can then publish it to CM so

that it can be configured and used. In a development environment where the expected (and