Aggregates -> BI Accelerator 

Description

Relational aggregates and the BI accelerator (BIA) allow you to improve the performance of BI queries when reading data from an InfoCube. They are redundant data stores in a BI InfoCube: In relational aggregates, data is stored in an aggregated form; in a BI accelerator index, however, data is compressed but not aggregated.

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.

The BI accelerator is particularly useful in cases where relational aggregates (or other BI-specific methods of improving performance such as database indexes) are not sufficient, are too complex, or have other disadvantages.

For more information, see Aggregates and BI Accelerator.

General Practices with Migration

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 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.

Unlike relational aggregates, BI accelerator indexes are only possible with InfoCubes that have cumulative key figures and not with InfoCubes that have non-cumulative key figures.