Adding a Custom Aggregation to a Dimension
Add a custom aggregation enhancement to a cube or dimension to replace the default aggregations that are associated with a dimension member with a different unary operator. This enhancement specifies a unary operator column in the dimension table that defines rollup for members in a parent-child hierarchy. The unary operator acts on the parent attribute in a parent-child hierarchy.
A custom aggregation is available only for dimensions that are based on existing data sources. For dimensions that were created without using a data source, you must run the Schema Generation Wizard to create a data source view before adding the custom aggregation.
To add a custom aggregation, you use the Business Intelligence Wizard, and select the Specify a unary operator option on the Choose Enhancement page. This wizard then guides you through the steps of selecting a dimension to which you want to apply a custom aggregation and identifying the custom aggregation.
Before you run the Business Intelligence Wizard to add a custom aggregation, make sure that the dimension that you want to enhance contains a parent-child attribute hierarchy. For more information, see Defining a Parent-Child Hierarchy.
On the first Specify a Unary Operator page of the wizard, you specify the dimension to which you want to apply a custom aggregation. The custom aggregation added to this selected dimension will result in changes to the dimension. These changes will be inherited by all cubes that include the selected dimension.
On the second Specify a Unary Operator page, you specify the parent attribute that you want for the custom aggregation and the source column in the dimension table for the unary operator. Parent attribute lists attributes that have their Usage property set to Parent. If there is more than one parent attribute, choose the parent attribute that corresponds to the parent-child relationship that you want to use. If there is no parent attribute listed, then the dimension does not have a valid parent-child hierarchy.
In Source column, you select the string column that contains the unary operators. (This selection sets the UnaryOperatorColumn property on the parent attribute.) The dimension table should also have a string column that specifies the unary rollup operator. The string values in this column should contain valid aggregation operators. If a row is empty, the corresponding member is calculated normally. If the formula in a column is not valid, a run-time error occurs when a cell value that uses the member is retrieved. For more information, see Using Unary Operators.