About Externally Aggregated Measures

If in the physical layer you assign a multi-dimensional measure an aggregation rule of External Aggregation, the Oracle Analytics query engine bypasses its internal aggregation mechanisms and uses the pre-aggregated measures.

When you import such a column into the logical layer, Semantic Modeler assigns these measures an aggregate value of None.

Use these guidelines to help you work with pre-aggregated measures:

• External aggregation only applies to multidimensional data sources that support these complex calculations.

• You can't assign external aggregation to measures from non-multidimensional data sources. If the Oracle Analytics query engine supports the required aggregation rule and the rule can be mapped to a relational data source, then it isn't complex and doesn't require external aggregation.

• There is only one aggregation rule for a logical measure. Therefore, a single logical column can't federate a non-complex aggregation rule for a mapping to a non-multidimensional source with a complex aggregation rule for a mapping to a multidimensional source. Instead, you need to create one logical measure for each source and then create a third logical measure that derives from the first two.

• You can mix non-complex measures from non-multidimensional data sources with non-complex measures from multidimensional data sources if they're aggregated through the Oracle Analytics query engine.