As noted earlier, a cross-cube formula can be used to calculate values in a Cube using data from another Cube or even two or more Cubes. For example, Cubes A and B contain sales data for Year 1 and Year 2 (Year 2 being current year). Cube C might contain forecasts for Year 3. A cross-cube formula, created in Cube C, could use values in Cubes A and B to average their sales data and dynamically calculate a percentage-based increase in sales, showing results in Cube C. The fact that the calculations are dynamic (true for all PowerOLAP formula calculations) means that changing a variable will automatically recalculate the formula driving the forecast in Year 3 (Cube C), therefore, forecasts would be updated as new “Actuals” are recorded for Year 2 (Cube B).
Another example worth mentioning—particularly beneficial for multinational companies—would be the use of a Cube that stores monthly foreign exchange calculations. One could multiply the data in this Cube by the figures in a Financials cube, where company units report in local currency, to determine all figures, by month, in US dollars, back in the Financials cube.
The use of cross-cube formulas can dramatically improve performance, enabling you to calculate values only for certain Member intersection points and show them in a “standalone” Cube, rather than design a single Cube that performs many calculations across all Member intersection points.
The following example is a cross-cube formula that will, again, yield figures for Margin % figures in the Sales cube—but this time based on a calculation from Margin % in the Margin cube.
In this case, we must account for the fact that the Reference cube (Margin) has more Dimensions than the Sales cube, where the formula results will be written. (This is instructive because the difference in dimensionality is often the case in cross-cube formulas.)
Our formula must instruct exactly which Members of the “extra Dimensions”—in Margin—to use in our calculation. Also, we need to indicate that Margin % in Sales will be based on Margin % in Margin.
1. Open the Sales cube and click Formula to open the Formula Editor dialog.
2. Copy and paste the LHS of the formula earlier for Margin % then type in the equals sign after ( = ).
3. Click on the Build Cube Reference button.
4. Select the Margin cube from the Cubes drop-down—since this is a cross-cube formula, with data originating in that Cube.
5. Click on Version in the Dimension list box on the left,
then select Actual in the Member list on the right.
6. Next, click on Year in the Dimension list box,
then select 2000 in the Member list.
7. Click on Margin Account in the Dimension list box,
then select Margin % in the Member list.
8. Click OK and return to the Formulas dialog box.
Type a semi-colon (;) at the end of the formula.
The dialog box appears as follows: