Construction and Test › Generating the Database › Database Generation

Database Generation

Database generation consists of two steps and is normally done by a Database Administrator.

1. Transform your logical data model into a physical data model.
2. Generate the necessary DDL (Data Definition Language) from the physical data model for the DBMS software to create the database.

   

The Data Model (or Entity Relationship Diagram) is often known as the Logical Data Model. For the most part, it is free of implementation-specific detail. To create a physical database, we have to first transform our logical Data Model objects into physical Data Model objects. The physical Data Model is actually represented in two diagrams, the Data Structure List diagram, and the Data Store List diagram. Collectively these two diagrams are sometimes known as the Technical Design.

In the Data Structure List diagram, you make implementation-specific structure changes and decisions such as:

• Reordering columns of a table
• Making indexes ascending or descending
• De-normalizing data between tables

In the Data Store List diagram, you make implementation-specific space allocation changes and decisions such as:

• Adjusting tablespace sizes
• Adjusting indexspace sizes