Performance Optimization with Aggregates 

Purpose

Relational aggregates allow you to improve the performance of BI queries when data is read from an InfoCube. The data of a BI InfoCube is saved in relational aggregates in an aggregated form. Relational aggregates are useful if you want to improve the performance of one or more specific BI queries, or specifically improve the performance of reporting on characteristic hierarchies.

In all other cases, if relational aggregates are not sufficient, are too complex, or have other disadvantages, we recommend that you use BI Accelerator (see Performance Optimization with SAP NetWeaver BI Accelerator).

Integration

Accessing the OLAP Processor

You can use relational aggregates and a BI accelerator index for the same InfoCube. A BI query always tries to use performance-optimized sources by checking the sources from which it can draw the requested data. It checks the sources in the following order:

...

       1.      OLAP cache

       2.      BI Accelerator index

       3.      Relational aggregates from the database

       4.      InfoCubes from the database

If an active BI accelerator index exists, the OLAP processor always accesses this BI accelerator index and not the relational aggregates. Therefore, with regard to modeling, we recommend that you create either relational aggregates or a BI accelerator index for an InfoCube.

Query Execution

When the query is executed, it is clear to the user whether data is being read from an aggregate, a BI accelerator index, or an InfoCube.

In the maintenance transaction, you can deactivate one or more aggregates on a temporary basis to test them for performance purposes or to analyze data consistency.

You can also execute the relevant query in the query monitor (transaction RSRT) using a corresponding debug option: Choose   Execute + Debug. In the Debug Options dialog box, choose Do Not Use Aggregates to execute the query with an InfoCube, as long as no BI accelerator index exists.