What is the difference between a logical and a physical database design?

A logical database design represents the abstract structure of the database, while a physical design details its actual storage.

In more detail, a logical database design is a conceptual representation of the data structures that are required by the database. It is independent of any hardware or software considerations. This design includes the identification and definition of relationships between data elements, rules for data integrity, security, and other aspects that define how data is organised and accessed. The logical design is typically created using a data modelling tool, which provides a graphical representation of the data structures and their relationships. This design is often used as a blueprint for the physical design. For more on how data is structured and the foundational concepts behind databases, see Understanding Data and Databases.

On the other hand, a physical database design is concerned with the actual implementation and storage of the data. It takes into account the specific hardware and software that will be used to store and retrieve the data. This includes considerations such as disk storage, indexing strategies, data access paths, and other technical specifications. The physical design is typically created by a database administrator, who uses the logical design as a guide. The role of the database administrator is crucial in optimising this process and can be further explored at Role of a Database Administrator (DBA). The physical design can have a significant impact on the performance and efficiency of the database. To understand different database models which might influence the physical design, refer to Database Models and Their Characteristics.

A-Level Computer Science Tutor Summary: In simple terms, logical database design is about planning what data the database will hold and how it's connected, without worrying about the technical details. It's like drawing a map of a city. Physical database design, on the other hand, focuses on how to build and store the database on computers, considering things like storage and how quickly data can be accessed.