IBM Cognos Dynamic Cubes

66 IBM Cognos Dynamic Cubes

4.2.5 Importing metadata

When you create a new project in Cognos Cube Designer, one of the steps you are asked to

do is to select a data source. The list of data sources you see are those Dynamic Query Mode

(DQM) data sources that exist in the Cognos BI Server environment that you have access to.

When you created the project, you were asked to authenticate with the Cognos BI Server

environment. The list of data sources you see is filtered to show only those DQM data

sources you have access to. If you do not see a data source that you believe you should have

access to, contact your Cognos system administrator to ensure that the correct level of

access is granted.

Generally, you should import the metadata from your reporting data warehouse before you

begin building the dimensions and cubes that will form your application. Although this is the

suggested workflow, you may begin building the framework for your cubes, dimensions, and

measure dimensions, and then import the metadata and perform a mapping exercise to

associate the level attributes with columns in your tables and views. If you are unfamiliar with

your data source, this workflow will be difficult to do; therefore, the suggested workflow is to

import metadata first.

When you select a data source for import, you are presented with a list of the schemas or

databases that you have access to. You may select the schema or database that you want to

use. After you select the schema or database, all objects that you have permission to access

will be imported. In many cases, importing mean the entire contents of the schema or

database. The permissions granted are determined by the credentials that were used when

configuring the data source in Cognos BI Server. If you notice that tables or views that you

were expecting to see are not imported, a permissions issue for the data source might be the

cause. Work with your Cognos system administrator and your DBA to resolve these issues.

After the import is complete, a tree view opens that contains all objects that were imported.

You can expand the tables and views, and select the individual columns to see their

properties in the Properties tab. The Data Source Explorer is a read-only control, so you may

not edit any object in that area.

You may import metadata from more than one data source into your project, however each

cube might contain objects that are sourced from a single data source. The ability to use

multiple cubes from multiple data sources is described in Chapter 6, “Virtual cubes” on

page 133. To import additional metadata from another data source or schema, click Get

Metadata on the toolbar. The list of available data sources, which you saw when creating the

project, are displayed. Repeat the import steps for the data source of your choice. An

accordion control is displayed in the Data Source Explorer so that the individual collections of

metadata are kept separate. You can toggle between these data sources by clicking the tab of

your choice in the Data Source Explorer.

4.2.6 Exploring data using the Relational Explorer Diagram

During the process of building your application, you might want to explore the data source you

are using, to either see what tables are related with primary-foreign key relationships, or how

a dimension table joins to the fact table. Alternatively, you might want to see the contents of

your data source in a more flexible view than the standard tree view in the Data Source

Explorer.

Cognos Cube Designer features an explorer diagram that you can use to see the tables and

views in your data source, and detect how the tables relate to one another. To open the

diagram, right-click a table in the Data Source Explorer control and select Explore Metadata.

The diagram opens and adds the selected table to the default view.