Create Successful Aggregates in BW
- by Robert Oliver, Investment Banking IT
- June 1, 2004
When used correctly, aggregates can optimize the performance of your BW system. The author demonstrates how to create base and lower-level aggregates that enhance system performance and he provides pre- and post-implementation tips to make the most of your aggregates.
Aggregates are an integral part of BW that, when implemented correctly, can optimize your system’s performance. I have worked on international BW implementations for five years, and perhaps the biggest area of frustration I have encountered has been in areas relating to aggregate use and management. My experience is not unique, and the headaches I’ve endured are common to most BW professionals, which is strange because aggregates are so important to a smoothly running system.
An aggregate is a subset of InfoCube data collected and stored into the InfoCube’s structure. Its purpose is to accelerate query response times by reducing the amount of data in the database for a query navigation step. Be aware, however, that aggregates have a down side. They are stored separately and can take up a lot of storage space. In addition, the more aggregates on the system, the longer the attribute change run takes after master data loads, especially if navigational attributes are used. SAP has created a “Know How” presentation1 on aggregates, which is available at http://service.sap.com/BW. It provides background information on aggregates and how they work technically but not much detailed information about how to set them up and maintain them properly.
My article complements much of the existing technical information like the SAP “Know How” presentation and provides you with a series of steps to help create aggregates for any BW system. Using readily available BW tools and background information, I will show you how to set up and optimize a base aggregate that can be used to build others that improve query run time without unnecessary system overhead for fills.
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