Data Independence:

Data Independence is a major feature of the database system and one of the most important advantages of the Three Level Database Architecture. As it has been discussed already that the file processing system makes the application programs and the data dependent on each other, I-e if we want to make a change in the data we will have to make or reflect the corresponding change in the associated applications also.

The Three Level Architecture facilitates us in such a way that data independence is automatically introduced to the system. In other words we can say the data independence is major most objective of the Three Level Architecture. If we do not have data independence then whenever there will be a change made to the internal or physical level or the data accessing strategy the applications running at the external level will demand to be changed because they will not be able to properly access the changed internal or physical levels any more. As a result these applications will stop working and ultimately the whole system may fail to operate. 

The  Data independence achieved as a result of the three level architecture proves to be very useful because once we have the data , database and data applications independent of each other we can easily make changes to any of the components of the system, without effecting the functionality and operation of other interrelated components.

Data and program independence is on advantage of the 3-L architecture the other major advantage is that ant change in the lower level of the 3-L architecture does not effect the structure or the functionality on upper levels. I-e we get external/conceptual and conceptual/internal independence by the three levels Architecture.

Data independence can be classified into two type based on the level at which the independence is obtained.

o         Logical Data Independence

o         Physical Data Independence

Previous

TOC

Next