Siebel Analytics Server Administration Guide > Creating and Administering the Business Model and Mapping Layer in a Repository > Creating and Administering Logical Columns >

Setting Default Levels of Aggregation for Measure Columns

You need to specify aggregation rules for mapped logical columns that are measures. Aggregation should only be performed on measure columns. Measure columns should exist only in logical fact tables.

You can specify an override aggregation expression for specific logical table sources. This helps the Analytics Server take advantage of aggregate tables when the default aggregation rule is Count Distinct. If you do not specify any override, then the default rule prevails.

To specify a default aggregation rule for a measure column

1. In the Business Model and Mapping layer, double-click a logical column.
2. In the Logical Column dialog box, click the Aggregation tab.
3. In the Aggregation tab, leave the aggregation Type as Simple and select one of the aggregate functions from the Default Aggregation Rule drop-down list.

   The function you select is always applied when an end user or an application requests the column in a query.

4. Click OK.