What is DBMS Architecture ?

DBMS Architecture shows the over all design of Database Management System.
Three Level Architecture of DBMS helps in design , develop , implement and maintain the Database Management System.
DBMS Architecture divides the Database System in to individual parts. Each part can be altered, replaced and changed separately.
Performance of the DBMS depends on DBMS Architecture.
3-tier architecture of DBMS helps in achieving the abstraction.
Abstraction is an important mechanism used to hide the internal irrelevant or complex detail of DBMS from the user.
Abstraction is achieved through the DBMS Three Level Architecture.

Some short questions are asked on the 3-tier architecture of DBMS in Technical Interview or viva voce and practical examination.

Advantages of three level architecture of DBMS are also discussed in this tutorial. These three levels of DBMS architecture are physical level, conceptual level and external level.

This tutorial is specially prepared for students who are doing graduation in computer science.

Frequently Asked Answers

By the end of this DBMS tutorial, students will be able to answer the following frequently asked questions.

What is DBMS?
What are the three levels of DBMS architecture?
Explain the DBMS architecture in detail with diagram.
What is an abstraction in the database?
How is the abstraction achieved in DBMS?
Define the term schema in the database?
Define the term data independence in the database?
What is logical data independence?
What is physical data independence?

Let’s start with introduction of three level architecture of a database system.

Three Level Architecture of DBMS

DBMS architecture is a three-level schema architecture used for database design to achieve abstraction in DBMS.
Database Management System Software is designed and developed by keeping in mind the three different schema levels in DBMS.
This DBMS architecture is used to describe the structure of a specific database system.
The advantages of this three level architecture of DBMS is that it helps separate the user and physical Database.
The 3 level architecture of DBMS makes the database design very easy and clear. All these three schemas physical schema , logical schema and external schema are also known as three-level, which are shown in the diagram and described below.

Different Levels of DBMS Architecture are as shown in above figure. Let’s understand them one by one.

Physical Level/Schema

The lowest level of architecture of a database system is the physical level in DBMS, also known as the internal level.
This physical level answer the questions how the data is stored in the database?
The data is stored in the external hard drives in bits and bytes at the physical level.
The physical level is also responsible for the Compression and Encryption of data.
Physical level in DBMS is indirectly used to describe complex level data structure in detail.
Physical level of DBMS is associated with physical DBMS Architecture.
Physical DBMS Architecture or Physical Level is responsible for allocating space to data.
Physical level in DBMS defines the physical storage structure of Database

Conceptual Level/Schema

The conceptual level is also known as the logical level.
The conceptual level of architecture of a database system specifies the relationships between various data tables and describes how the database looks to the users conceptually.
The conceptual level does not have any relation to how the data in the database is stored.
The conceptual level answer the question what data is stored in the database ?
The conceptual level of database architecture describes the structure of the whole database.
At a conceptual level, internal detail such as the implementation of data is hidden. This concept is also known as Data Abstraction.
Generally, programmer and administrator work at conceptual or logical level.
Conceptual Level defines all entities of database , their attributes and their relationship.
Conceptual Schema also defines the security and integrity of the Database.

External Level

The highest level in the 3 tier architecture of DBMS is the external level and closest to the user. It is also called the view level or superficial level.
This schema also contains subschema. Each subschema describes each view of the database.
External level shows only the relevant data to the users in the form of views and hides the remaining data.
All individual user can see the data as a different view as per their requirements.
External level of three schema architecture in DBMS describes database part that a user or a particular group of the user is interested in and hide remaining database from that user or group of user.

One important thing to keep in mind is that during the designing of database architecture programmer or designer make the data independence among these three levels of database architecture.

Importance of DBMS Architecture

Database architecture is important because it mainly focuses on maintenance, design and overall administration of the database management software.
Three level architecture of DBMS affects database management software performance. If DBMS architecture is correct, it becomes easy to access and perform the operation in a more efficient manner.

Conclusion and Summary

The following points were discussed in this tutorial.

DBMS three level architecture is used to achieve abstraction in a database.
Three levels of DBMS are Logical Level, Physical Level and External Level.
Three level of architecture of a database system makes the design easy and clear.
Physical level or internal level answer the questions how the data is stored in a database ?
The logical level or conceptual level answer the questions about what data is stored ?
External level or view deals with how the data or what data should be visible or accessible to the external user.
we explained architecture of DBMS with diagram.

I hope this database management system architecture tutorial will be helpful for computer science students.