A semi-additive measure can be aggregated along some, but not all, dimensions that are included in the measure group containing the measure. For example, Opening Balance and Closing Balance can be more efficiently calculated using semi-additive functions. Intellicus provides First Child and Last Child measures’ aggregation. Opening balance will be first child measure and Closing balance will be last child measure. Semi-additive measures work for ‘Time’ dimension type only.
Semi-additive aggregation is extremely useful when you have a fact table that contains snapshot data.
For example, if you have a fact table containing information on the number of items in stock in a warehouse, then it would not make sense to aggregate these measures over time: if you had ten widgets in stock on January 1, eleven in stock on January 2, eight on January 3 and so on, the value you would want to display for the whole of January would never be the sum of the number of items in stock on each day in January. The value you require depends on your organization’s business needs.
Figure 12: Semi-Additive Measure
For each measure, you can select from the types of semi-additive functionality described in the following table.
|Average Over Time||The aggregation of a member is the average of its children. For example, if you have two dimensions Time & Location and one measure; then the measure value will be shown as average of its children. But if you remove Time dimension, the measure value will be shown as sum of its children.|
|First Child||The member value is evaluated as the value of its first child along the time dimension.|
|First Non-Empty Child||The member value is evaluated as the value of its first child along the time dimension that contains data.|
|Last Child||The member value is evaluated as the value of its last child along the time dimension.|
|Last Non-Empty Child||The member value is evaluated as the value of its last child along the time dimension that contains data.|
You can select the ‘Time’ type dimension you wish to apply semi-additive function on under the Compute Over drop-down.