A2oz

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

Published in Database Design 2 mins read

Logical database design and physical database design are two distinct phases in the database design process, each focusing on different aspects of the database structure.

Logical Database Design

The logical database design focuses on the data itself and how it is organized and related. It defines the entities, attributes, and relationships between them, without considering the specific implementation details.

  • Focus: Data structure and relationships
  • Outcome: Entity-Relationship Diagram (ERD)
  • Example: Defining an entity called "Customer" with attributes like "Name," "Address," and "Phone Number," and establishing a relationship between "Customer" and "Order" entities.

Physical Database Design

The physical database design takes the logical design as input and translates it into a concrete implementation. It considers the specific database management system (DBMS) and hardware environment to optimize performance and efficiency.

  • Focus: Database storage, indexing, and access methods
  • Outcome: Database schema, tables, indexes, and storage structures
  • Example: Choosing a specific data type for the "Phone Number" attribute, creating indexes to speed up searches, and selecting an appropriate storage structure for the "Order" table.

Key Differences

Feature Logical Database Design Physical Database Design
Focus Data structure and relationships Database implementation and optimization
Outcome Entity-Relationship Diagram (ERD) Database schema, tables, indexes, and storage structures
Level of Detail High-level, abstract Low-level, specific
Dependencies Independent of specific DBMS Dependent on chosen DBMS
Implementation Conceptual, not directly implemented Concrete, implemented in a database

In Summary

Logical database design focuses on the data model, while physical database design maps that model to a specific database implementation. The logical design ensures the integrity and accuracy of the data, while the physical design optimizes the performance and efficiency of the database.

Related Articles