In SAP BW, why can we not create an aggregate on an Operational Data Store (ODS) or DataStore Object, whereas aggregates are defined on InfoCubes?

Introduction / Context:
In SAP BW, InfoCubes and Operational Data Store or DataStore Objects serve different purposes. InfoCubes are designed as multidimensional structures optimized for analytical queries, while ODS or DataStore Objects hold detailed, line item level data. Aggregates are performance structures built on top of InfoCubes to pre summarize data. This question asks why similar aggregates are not created on ODS or DataStore Objects.

Given Data / Assumptions:

• We are using SAP BW concepts, including InfoCubes and ODS or DataStore Objects.
• Aggregates are known to improve query performance on InfoCubes by storing pre aggregated data.
• ODS or DataStore Objects contain detailed transactional or delta data.
• The question focuses on design and modeling differences, not on authorization or licensing.

Concept / Approach:
Aggregates in SAP BW are built on InfoCubes because InfoCubes are multidimensional, with fact tables and dimension tables that map naturally to summarized slices along hierarchies. An ODS or DataStore Object, by contrast, is a flat, key based table structure that stores detailed records, often closer to normalized form. It is meant for detailed reporting and staging rather than multidimensional aggregation. Since aggregates are conceptually and technically tied to the cube model, they are not defined on ODS or DataStore Objects, which would not benefit in the same structured way.

Step-by-Step Solution:
Step 1: Recall that an InfoCube uses a star schema with fact and dimension tables and is the main target for OLAP analysis in SAP BW. Step 2: Understand that aggregates are smaller cubes that summarize an InfoCube at higher levels of granularity to speed up queries. Step 3: Recognize that an ODS or DataStore Object stores line item level data in a flat table keyed by primary keys and is optimized for detailed reporting and data staging. Step 4: Because this structure is not a star schema, the standard aggregate mechanism used for InfoCubes does not apply. Step 5: Option a correctly explains that ODS or DataStore Objects are detailed, flat structures and that aggregates are defined only on multidimensional InfoCubes.

Verification / Alternative check:
SAP BW documentation on aggregates states that they are defined only for InfoCubes. It explains that aggregates contain a subset of InfoCube data at a summarized level. Guidance for ODS or DataStore Objects emphasises their role for detailed reporting and data consolidation, not for multidimensional aggregation via cube aggregates. This difference aligns with the explanation in option a.

Why Other Options Are Wrong:
Option b is wrong because ODS or DataStore Objects can indeed contain numeric key figures. Option c incorrectly states that ODS objects are file based and that aggregates are only for relational databases; in reality, all of these structures sit on a database. Option d claims that ODS objects automatically create aggregates, which they do not. Option e suggests that ODS or DataStore Objects cannot be used for reporting at all, which is incorrect because they can be used directly as reporting providers.

Common Pitfalls:
A common misunderstanding is to assume that every data structure in SAP BW supports aggregates in the same way. Another pitfall is to model all data as ODS objects and then expect cube like performance for summary queries. Understanding the distinct roles of InfoCubes and ODS or DataStore Objects helps you choose the right provider type for each reporting scenario.

Final Answer:
You cannot create aggregates on an ODS or DataStore Object because it stores detailed, flat records rather than multidimensional cube data, and aggregates are a feature specific to multidimensional InfoCubes, as described in option a.