Calculating Essbase Databases
In This Section:
The information in this chapter applies only to block storage databases and is not relevant to aggregate storage databases.
Also see:
- Values that you enter, called input data
- Values that are calculated from input data
- You enter regional sales figures for a variety of products. You calculate the total sales for each.
- You enter the budget and actual values for the cost of goods sold for several products in several regions. You calculate the variance between budget and actual values for each product in each region.
- The database contains regional sales figures and prices for all products. You calculate what happens to total profit if you increase the price of one product in one region by 5%.
Small differences in the precision of cell values may occur between calculations run on different platforms, due to operating system math library differences.
Most computers represent numbers in binary, and therefore can only approximately represent real numbers. Because binary computers cannot hold an infinite number of bits after a decimal point, numeric fractions such as one-third (0.3333...) cannot be expressed as a decimal with a terminating point. Fractions with a denominator of the power of two (for example, 0.50) or ten (0.10) are the only real numbers that can be represented exactly. See IEEE Standard 754 for Floating-Point Representation (IEEE, 1985).
Outline calculation is the simplest calculation method. Essbase bases the calculation of the database on the relationships between members in the database outline and on any formulas that are associated with members in the outline.
For example, Figure 107, Relationship Between Members of the Market Dimension shows the relationships between the members of the Market dimension in the Sample.Basic database. The values for New York, Massachusetts, Florida, Connecticut, and New Hampshire are added to calculate the value for East. The values for East, West, South, and Central are added to calculate the total value for Market.
Figure 108, Calculation of Variance and Variance % shows the Scenario dimension from the Sample.Basic database. The Variance and Variance % members are calculated by using the formulas attached to them.
It may be more efficient to calculate some member combinations when you retrieve the data instead of calculating the member combinations during the regular database calculation. You can use dynamic calculations to calculate data at retrieval time. See Dynamically Calculating Data Values.
Calculation script calculation is the second method of calculation. Using a calculation script, you can choose exactly how to calculate a database. For example, you can calculate part of a database or copy data values between members.
A calculation script contains a series of calculation commands, equations, and formulas. For example, the following calculation script increases the actual marketing expenses in the New York region by 5%.
FIX (Actual, “New York”) Marketing = Marketing *1.05; ENDFIX;
Figure 109, Calculating a Multidimensional Database, which is based on a simplified database, illustrates the nature of multidimensional calculations:
The Time dimension has four quarters. The example displays only the members in Qtr1—Jan, Feb, and Mar.
An intersection of members (one member on each dimension) represents a data value. The following example has three dimensions; therefore, the dimensions and data values in the database can be represented as a cube, as shown in Figure 110, Three-Dimensional Database:
As shown in Figure 111, Sales, Actual, Budget Slice of the Database, when you refer to Sales, you are referring to a slice of the database containing eight Sales values.
As shown in Figure 112, Actual, Sales Slice of the Database, when you refer to Actual Sales, you are referring to four Sales values:
To refer to a specific data value in a multidimensional database, you must specify each member on each dimension. A data value is stored in one cell in the database. In Figure 113, Sales, Jan, Actual Slice of the Database, the cell containing the data value for Sales, Jan, Actual is shaded.
In Essbase, member combinations are denoted by a cross-dimensional operator (->). Sales, Jan, Actual is written as:
Sales -> Jan -> Actual
When Essbase calculates the formula “Margin% = Margin % Sales,” it takes each Margin value and calculates it as a percentage of its corresponding Sales value.
- Margin -> Jan -> Actual as a percentage of Sales -> Jan -> Actual. The result is placed in Margin% -> Jan -> Actual.
- Margin -> Feb -> Actual as a percentage of Sales -> Feb -> Actual. The result is placed in Margin% -> Feb -> Actual.
- Margin -> Mar -> Actual as a percentage of Sales -> Mar -> Actual. The result is placed in Margin% -> Mar -> Actual.
- Margin -> Qtr1 -> Actual as a percentage of Sales -> Qtr1 -> Actual. The result is placed in Margin% -> Qtr1 -> Actual.
- Margin -> Jan -> Budget as a percentage of Sales -> Jan -> Budget. The result is placed in Margin% -> Jan -> Budget.
- Essbase continues cycling through the database until it has calculated Margin% for every combination of members in the database.
For information about how Essbase calculates a database, see Defining Calculation Order.
By default, the calculation for a database is a CALC ALL of the database outline. CALC ALL consolidates all dimensions and members and calculates all formulas in the outline.
You can, however, specify any calculation script as the default database calculation. Thus, you can assign a frequently used script to the database rather than loading the script each time you want to perform its calculation. If you want a calculation script to work with calculation settings defined at the database level, you must set the calculation script as the default calculation.
When you use Administration Services to calculate a database, you can execute the calculation in the background so that you can continue working as the calculation processes. You can then check the status of the background process to see when the calculation is complete.
To calculate a database, use a tool: To stop a calculation before Essbase completes it, click the Cancel button while the calculation is running.
How Essbase handles the cancellation depends on the Essbase Kernel Isolation Level settings. See Understanding Isolation Levels.
- Serial calculation (default): All steps in a calculation run on a single thread. Each task is completed before the next is started.
- Parallel calculation: The Essbase calculator can analyze a calculation, and, if appropriate, assign tasks to multiple CPUs (up to four).
To calculate a database, you must have Calculate permissions for the database outline. With calculate permissions, you can calculate any value in the database, and you can calculate a value even if a security filter denies you read and update permissions. Carefully consider providing users with calculate permissions.
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