Development Process: Planning and Modeling Phase
The figure shows all eight stages, including the tools that can be used in each stage for software-based data warehouse development. In this unit, you will learn how the Planning and Modeling phases are implemented.
Data Models Represent the Entirety of Data Relevant in a Domain
Models play an essential role when it comes to database development. They represent a formal description of objects and how they relate to one another and to properties of real world (business) entities. Data modeling is the process of creating a data model by applying formal data model descriptions. It is a technique for defining business requirements for a database. It is common practice to start with an Aggregated Conceptual Data Model which is refined to a Detailed Conceptual Data Model, which is then transformed to a Physical Data Model.
Modeling Can be Done Top-down or Bottom-up
Top-down Modeling Approach
The top-down approach starts with a pure business perspective on the information. The goal is to describe how exactly the business works. This is done by the business analyst in collaboration with the specialized departments utilizing the CDM. Exact components and requirements are determined through meetings and respective documentations. It is important that all parties involved always keep in mind that requirements must be feasible. The implementation of the PDM on SAP HANA is done with help of SAP HANA Web IDE and Git.
Example: Aggregated Conceptual Data Model
The detailed CDM is derived from the aggregated CDM. It is less abstract and includes all attributes and all data domains (data types and lengths).
Example: Detailed Conceptual Data Model
However, it does not yet contain database-specific objects (such as views, indexes, and so on).
Example: Physical Data Model
Based on the detailed CDM, a physical data model is created. In our approach it is based on the Data Vault modeling method, using hubs, links, and satellites. When the PDM is fully specified, it contains all database objects that are necessary for the implementation (such as tables, indexes, constraints, triggers, and so on).
Bottom-up Modeling Approach
Utilizing the bottom-up modeling approach, the Physical Data Model is created on the basis of an existing database. This process is called reverse engineering and is provided as a feature of the SAP PowerDesigner. The reverse-engineered PDM is then refined until it meets the business requirements. Similarly to the top-down modeling approach, the final PDM is implemented on SAP HANA with the help of SAP HANA Web IDE and Git.