Best Practices for SAP BI using DB2 9 for z/OS - IBM Redbooks

12.9 Compression of requests
Data is loaded into an InfoCube by using smaller pieces, called requests. The
data is first stored in the F- fact table of the InfoCube. Requests can be deleted
from the F- fact table if, for example, the data is inconsistent. If the quality status
of a request is appropriate, the request can be compressed, which significantly
reduces the required storage space for the data.
This form of compression is called SAP compression and is a consolidation and
summarization of data from the InfoCube’s F-fact table into its E- fact table.
Compression results in the package ID being stripped off and all records
summarized into the E-fact table.
During compression, data is transferred from the F- fact table to the E- fact table
of the InfoCube or aggregate, as shown in Figure 12-9. Compressed requests
can only be deleted by deleting the entire contents of the InfoCube.
Figure 12-9 Compression of requests
12.10 DataStore (DSO)
Request 1 to n
E- Fact table (compressed data)
Condensor
Request n Request n+2 Request n+3
F- Fact table (uncompressed)
A DSO object stores consolidated transaction data from one or several
InfoSources. In contrast to the multidimensional data models of InfoCubes, data
in DSO objects is stored in flat, transparent, database tables. DSO object data
Chapter 12. Concepts, activities, and terminology 273