OBIEE Tricky Question

Q.No: Can we refresh repository variables from answers side?
Ans. No, we can’t refresh repository dynamic variables from answers side. We have utility to refresh those in RPD. We can schedule the timing for refreshing dynamic repository variables.

Q.no. Can we do reporting on two different data sources? if yes, what’s the approach ?
Yes, we can create reports on the data coming from two different datasources. For that there should be relationship between the tables. Import the tables from the two datasources in physical layer. Create alias on the tables and join them. Now create a Logical model in BMM and drag those tables in BMM. After that you can expose them in Present layer.

Qno. Can we create single hierarchy on multiple dimension tables?
Yes, it can also be achieved. For this there should be some relationship between the two tables. Create multiples LTS in this scenario to make the model as star schema and on top of that create your level based hierarchy. 

Q.no. what is no of elements at each level in Dimensional Hierarchies?

Ans: Each logical level of each dimensional hierarchy contains a setup named “Number of Elements at this Level”.

This setup number is used by the Oracle BI Server when defining strategy for picking optimal aggregate physical source for a query. The numbers in the setup will help determine which physical table is most appropriate for a better performance query return.

These values should be changed to ratio values based on Actual data in the implementation. To prevent problems with aggregate navigation, make sure these numbers illustrate reality, mainly in the way the compare to each other.

Fact sources will be selected on a combination of:

• the fields selected as well as
• the levels in the dimensions to which they link.

For example, when aggregate navigation is used, multiple fact sources exist at different grains. The Oracle BI Server multiplies the number of elements at each level for each qualified source as a way to estimate the total number of rows for that source.

Then, the Oracle BI Server compares the result for each source and selects the source with the lowest number of total elements to answer the query. The source with the lowest number of total elements is assumed to be the fastest.

By adjusting these values, you can alter the fact source selected by Oracle Business Intelligence in some cases.

For the Grand Total level, leave this field blank. The system will set to a value of 1 by default.