Aggregation 
The selected key figures are aggregated in the OLAP engine of the BW system. The aggregation behavior determines how key figure values are aggregated in queries that use different characteristics and characteristic values.
In order to calculate the values of key figures, the data from the InfoProvider has to be aggregated to the detail level of the query and formulas may also need to be calculated. The system has to aggregate using multiple characteristics.
The basic form of the aggregation is the Standard Aggregation. The system can aggregate key figures as part of the standard aggregation according to the following rules: Summation (SUM), Minimum (MIN), and Maximum (MAX). The standard aggregation is independent from a specific characteristic. The system executes the standard aggregation of all chractertistics that are not in the breakdown, irrespective of their sequence. This is the most well-known aggregation behavior.
Note
In DataStore objects for writing directly, it is also possible in planning mode to use key figures with the standard aggregation NO2, no aggregation (X if more than one value appears).
In addition to the standard aggregation, there is also the Exception Aggregation. The aggregation rules for the exception aggregation depend on a characteristic. You define how a restricted, calculated key figure or formula is aggregated in the Analytic Engine with regard to one or more reference characteristics. (Calculated key figures and formulas mostly behave correspondingly; Only in exceptions can there be differences in the query results). A characteristic is needed for the exception aggregation in order to define the granularity on the basis of which the aggregation rule is applied. The system aggregates the key figures to this detail level according to the rules of the standard aggregation. The exception aggregation is also always an extension to, and not a replacement for, the standard aggregation.
Example
Let us consider aggregation rule (AVG) as an example: The system calculates the average from the sum of all values and divides is by the number of entries. To define the number of entries, a granularity of data must be defined to which the system is to aggregate the multi-dimensional data according to the rules of the standard aggregation. The result of the standard aggregation is the starting point of the exception aggregation, as the basis for the calculate according to the rule Average of All Values.
Recommendation
From a business point of view, for example, the exception aggregation occurs if warehouse stock cannot be totalled up at the time or if the counters that count the number of characteristics for a specific characteristic.
You can find an overview of the aggregation rules in the system under Rules for Standard and Exception Aggregations.
Activities
You define the different types of aggregation behavior of standard and exception aggregations for basis key figures in the InfoObject maintenance (see Tab Page: Aggregation): For forrmulas and calculated key figures in the BEx Query Designer (see Properties of Selection/Formula/Cell).
Note
You can also overwrite the settings for aggregation with the settings in the query. In the documentation for the general analysis functions in BEx, see the sections Local Calculations, Calculate Results as..., and Calculate Single Values as... (Local Aggregation).