Where you derive a Fact is Important

When you define a calculated measure column using a logical column, OBIEE performs the aggregation for the columns used in the calculation first, before applying the calculation.

So for example, if a calculated measure (Total Revenue) is derived from the product of two LOGICAL columns (Unit Price x Number of Items), then OBIEE will create SQL such that the Unit Price and Number of Items columns are aggregated first, and then the multiplication.

However, if the calculated measure is derived from the product of two PHYSICAL columns, then the multiplication will be executed first, and then the aggregation after.

This can make a difference in some cases, so know what you want to accomplish and then carefully choose the appropriate column type for your derived column.