Three Level Architecture of DBMS
Three Level Architecture:
The generalized architecture of a database system says ANSI/SPARC model. Many commercial systems and research database models fit within this framework. This architecture also says Three-Level Architecture of DBMS. It consists of many PCs and a workstation. This architecture depends upon how the users connect to the database. The Three-Level Architecture of the DBMS diagram is given below:
3-Tier Architecture in DBMS:
In DBMS, The 3-Tier architecture contains another layer between the client and server. In this architecture, the client can’t directly communicate with the server. The 3-Tier architecture uses for large web applications. It divides into the following three levels:
1. External or View level
2. Conceptual level
3. Internal or Physical level
External or View level:
The external or view level of the architecture of a Database system is the level closest to the users. This level is concerned with how the data are observed. So, most of the users of the database are not concerned with all the information.
It describes that different types of data stored in a database. This level also includes the relationships existing among data items. At this level, a database is also described logically rather than physically in terms of data structure.
However, the users of this level are not concerned with how these logical data structures will be implemented at the physical level. Rather, they are only concerned about what information would be kept in a database.
The lowest level of abstraction is the internal level. It is the one closest to the physical storage device. So, it is also termed as physical level. Because it describes how data are stored on the storage medium such as a hard disk, magnetic tape, etc. The Internal level also defines compression and encryption techniques.
Advantages of Three Level Architecture of DBMS:
i. Logical and physical separation of functionality
ii. Faster development
iii. Improved security
iv. Improved reliability
v. Improved scalability