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
Ye a r
Sto r e s
St a t e
St o r e
Year Quarter Coun try Stat e Cit y Cos t
Year Quarter Month Country Cost
Year Country State Cost
Month Store Cost
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:
Multiple hierarchies per dimension
Parent-child (recursive) hierarchies
Time hierarchies, including automatic creation of relative time members
Calculated (dimensional) members and measures
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