Aggregates 

Definition

An aggregate is a materialized, aggregated view of the data in an InfoCube. In an aggregate, the dataset of an InfoCube is saved redundantly and persistently in a consolidated form in the database.

Use

Aggregates allow you quick access to InfoCube data in reporting. Similar to database indexes, they serve to improve performance.

Aggregates are particularly useful in the following cases:

·        Executing and navigating in query data leads to delays where you have a group of queries

·        You want to speed up the execution and navigation of a specific query

·        You often use attributes in queries

·        You want to speed up reporting with characteristic hierarchies by aggregating specific hierarchy levels

Structure

An aggregate is made up of the characteristics and navigation attributes belonging to an InfoCube. Characteristics that are not used in the aggregate are compressed.

Every component of an aggregate has to be assigned to a selection type. A selection type indicates the degree of detail to which the data in the underlying InfoCube is aggregated. You can choose one of the following selection types:

·        All characteristic values ("*"): The data is grouped by all values of the characteristic or navigation attributes (see Selection Type "All Characteristic Values" (‘*’))

·        Hierarchy level (“H”): The data is grouped by the hierarchy level node You can also store values on hierarchy levels of an external hierarchy (see Selection Type "Hierarchy Level" (‘H’))

·        Fixed value (‘F’): The data is filtered by a single value (see Selection Type "Fixed Value" (‘F’))

Both time-dependent attributes and time-dependent hierarchies can be used in aggregates.

Integration

If you have created an aggregate for an InfoCube, activated it and entered data for it, the OLAP processor can access these aggregates automatically. For more information about the order in which access is performed, see Aggregates and HPA Indexes. The different results are consistent when you navigate in the BI query. The aggregate is transparent for the end user.

New data is loaded to an aggregated at a defined time using logical data packages (requests). After this operation, rollup, the new data is available in reporting (see System Response Upon Changes to Data)

 

See also:

“Performance Tuning for Queries with BW Aggregates” on the performance page for SAP NetWeaver Business Intelligence in SAP Service Marketplace