Database Architecture and Components

Database Systems




Unit – 2
Database Architecture and
Components




Database Systems Slide 1

, Database Architecture
• To support data independence and multiple user views,
DBMS employs the following three level architecture.
1. External Level / Layer
2. Conceptual Level / Layer
3. Internal Level / Layer
• This architecture is also called ANSI-SPARC architecture
proposed by Standards Planning and Requirements
Committee (SPARC) of ANSI.
• The objective of the three-level architecture is to separate
each user’s view from the way database is physically
represented.


Database Systems Slide 2

, Database Architecture

External External External
View- 1 View- 2 View- n
External / Logical Data
Conceptual Mapping Independence



Conceptual Level
Conceptual / Physical Data
Internal Mapping Independence




Physical Level

Database Systems Slide 3