There are static and dynamic repository variables.
Note:
Variables in the Oracle BI Server can be either repository or session variables, and are defined using the Variable Manager within the Oracle BI Administrator (Manage > Variables).

This brings up the Variable Manager, that divides variables out into repository and session variables, with a further subdivision into static and dynamic repository ones and system and non-system session ones. You can also define variables at the Presentation Server level, these are scoped to individual dashboards and are used amongst other things for setting dashboard prompt values and integrating the dashboard with BI Publisher parameters. Here's a screenshot of a typical Variable Manager screen.

After creating your base metrics, try using the Calculation Wizard to automate the process of creating time- series metrics or comparison metrics such as: Change, Percent Change, Index, and Percent. The Wizard may save you many hours of time and frustration, especially if you have to create more than a handful of these metrics. In addition, the Wizard allows you to include customized logic to handle nulls in the base metrics.
You may refer to the Oracle documentation for further detail.

B: Example:
1. Configure the new source table to have the 'logical level' under the content set to 'Countries' (the summarized level)

b
2. Do the similiar setting for dimension table
Now when user query the data at 'Counties' level, the query will be redirected to these summary table instead of the more detail fact table Note: Aggregate tables are Physical tables that store Aggregates of measures across multiple levels of a Hierarchy.

Denormalization is the process of intentionally backing away from normalization to improve performance by suppressing join and permitting the use of star transformation technique.
Denormalization should not be the first choice for improving performance and should only be used for fine tuning of a database for a particular application.

B: Click Refresh All from the Oracle BI menu in PowerPoint to refresh all the refreshable objects in the presentation.
C: Right-click Table and select Insert as List from the shortcut menu. The Edit Prompts and Levels dialog box appears. Accept the default options and click Insert.