What is it?
Use SUM to aggregate a measure up to the defined hierarchy level in the dimension. You can SUM one or more dimensions. This is often used for summary tables to remove details from the source detailed table. The resulting measure will be displayed at the higher level with the details removed.
How to write it?
Fx layout: = SUM(Table.Measure, Dimension1.LevelA, Dimension2.LevelB, etc.)
Example:
Example = SUM(Employee plan.Headcount, Time.Quarter, All Cost centers)
Will result in the Headcount measure from the Employee plan table being displayed at the Quarter and all (total) cost center levels. This will remove months and individual cost centers (and other hierarchy levels below all).
Alternative: If using SUM for display, consider using table views?
Using a new table view and updating display may be more efficient to achieve the same presentation.
Related measure: Arithmix Functions: SUMBY (aggregating measures and eliminating dimensions)