Analytical View of Business Information Warehouse Model
SAP�s BW is based on "Enhanced Star schema" or "Info Cubes" database design. This database design has a central database table, known as �Fact Table� which is surrounded by associated dimension tables. These dimension tables contain references to the pointer tables that point to the master data tables which in turn contain Master data objects such as customer, material and destination country stored in BW as Info objects. An InfoObjects can contain single field definitions such as transaction data or complex Customer Master Data that hold attributes, hierarchy and customer texts that are stored in their own tables.
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The BW product is designed to store all business-critical information contained in the R/3 OLTP (online transaction processing) system and other non-SAP systems in a form that is easy to access and analyze using the BW client tools.
The database design used to meet these objectives is an "Enhanced Star Schema" or "InfoCube" (the data against which the end user runs queries).
The info cubes and master data tables that are used in a BW system are generally unique to that system as shown in the figure below:
Fig: SAP BW Database Design
The complexity of the objects in this design leads to the challenge of maintaining up-to-date and accurate data in all the BW data tables. However, loading data into the BW is accomplished by using InfoPackages. InfoPackages are tools for organizing data requests that are extracted from the source system and are loaded into the BW system. With the progress of BW project the number of info packages increases emphasizing the importance of good performance of each info package. Although the DBMS underlying the BW system is monitored by the standard software�s for the R/3 functionality but this leaves a gap between the table spaces and table names as they appear at the DBMS level and the BW application level entities to which these objects belong. To bridge this gap, the new BW functionality for R/3 includes reports that place DBMS objects in a BW context. These reports allow the user to take an object at the DBMS level and associate it with its application-level entity.
In case of any problem in order to enable the administrator to identify the problem the InfoPackages are organized on the basis of the object to which they are transporting data- Info cube, ODS or Master Data. The overall request status for the object is displayed, and an alarm is triggered if any Info Package run from any Info Source fails. In this way, the administrator is able to locate the exact position where a failure is going to impact the users and the BW system. Also, for InfoCubes, Master Data and the ODS to give an overview of the history of requests for the system, the progress of the last N requests through each stage of extraction and load is displayed, and for any failures, the step that failed is displayed. The performance of requests can be monitored by display of performance statistics for each stage of extraction and load in the form of graphs.
