Three-Level Architecture
Learn the purpose of the three-level database architecture and how it separates what users see from how data is structured and stored.
We'll cover the following...
Have we ever wondered how an online store, like Amazon, can show us a personalized homepage with our order history, while a warehouse manager sees a completely different screen with stock levels and supplier details, and a data analyst sees yet another view for sales reports?
They are all accessing the same database, but they see it in ways tailored to their specific needs.
This magic is made possible by a clever design principle known as the three-level architecture. It separates what the user sees from how the data is actually stored, making databases incredibly flexible and powerful. In this lesson, we’ll explore this foundational concept.
By the end of this lesson, we will be able to:
Understand the purpose of the three-level database architecture.
Describe the external, conceptual, and internal levels.
Explain the crucial concepts of logical and physical data independence.
Appreciate how this architecture makes databases robust and easy to maintain.
Three-level architecture
The three-level architecture, also known as the ANSI-SPARC architecture, is a foundational framework for designing database systems.
Its primary objective is to separate the user’s view of the data from the way the data is physically stored. Consider this: if every application needed to know the exact location and storage format of data on a disk, even minor changes—such as relocating a data file or optimizing a storage structure—would necessitate rewriting all related applications.
Clearly, that would be a maintenance nightmare.
The ANSI-SPARC architecture addresses this challenge by introducing three distinct layers of abstraction, or levels. Each level serves a specific ...