Explanation/Reference:
You can define calculations in either of the following ways:
- Before the aggregation, in the logical table source. For example:
sum(col_A *( col_B))
- After the aggregation, in a logical column derived from two other logical columns. For example:
sum(col A) * sum(col B)
Incorrect answers:
A: Defining the Logical Key of a Fact Table
Foreign Key Logical Joins
If foreign key logical joins are used, the primary key of a logical fact table should then be comprised of the foreign keys. If the physical table does not have a primary key, the logical key for a fact table needs to be made up of the key columns that join to the attribute tables as follows:
1.Look at the foreign keys for the fact table and find references for all of the dimension tables that join to this fact table.
2.Create the logical key of the fact table as a combination of those foreign keys.
B: You can find this functionality in the general property of a subject area in the repository.
The goal of this definition is to guide the BI Server to make the best choice between two possibles query path.
Multiple path occurs when, if you choose two attributes of dimensions that links together to two fact tables.
For instance, this case can occurs when you create for instance a constraint dashboard prompt.
To guide OBIEE in the best choice, you need to select a fact attribute (measure) as an implicit fact column.
C: What are the benefits of using Aliases in OBIEE?
It is a best practice to create aliases for all tables. Aliases are created in the Physical Layer of the repository. Some of the benefits of using aliases are given below:
You can create a join relationship which is different than the actual foreign key relationship in the database. This helps in defining relationships to meet business model criteria.
An alias is used to avoid circular joins and to configure self joins. (for more details on Fan Trap and Circular Joins check this blog.)
Aliases can function in numerous ways to define business model e.g. a table can act both as a dimension and a fact using aliases.
You can rename aliases to make physical and business model easier to understand.