Data Modeling in SAP HANA – Introduction
With S4 and Hana Database, SAP is getting rid of the aggregation tables. Two obvious questions here are What are the aggregation tables and Why SAP is dropping them?
Let’s take the What first. When I started working in SAP in 2006, I was told that SAP keeps in such a way that the same data is not repeated multiple times. For example, General Properties of materials are stored in MARA (where the primary key is material) but the plant-specific properties of the material are stored in the MARC table (where plant and material both are primary keys). If the general properties of materials are stored in the MARC table, then those values will repeat for the same materials stored in different plants. For this reason, SAP built several tables to keep a specific set of data, especially for transactional data. These tables are called the aggregate table. This ensured lower data footprint and easy read access.
Now let’s come to Why – With column store, now the repeated data across columns do not need to save multiple times. This means you can dump information in one table – SAP calls it Simple (you may recall Simple Finance, Simple Logistics etc). So data footprint is no longer an issue. Unfortunately, humans and applications cannot make sense of column stored data. SAP has provided virtual data modeling capabilities to make any aggregation table (as per your design).
As aggregation can be made on-demand now, there is no need to keep such database tables.
Data Modeling is the default way for new SAP to read data for applications. It is easy to learn Data Modeling but needs a good deal of experience to do it right. In future blogs, we will discuss – how to effectively create data models. Like our LinkedIn page and follow this blog to keep updated.
