Data independence refers to the concept in database management systems (DBMS) where the applications or programs accessing the data are isolated from the underlying physical storage structures or changes made to the data organization. It allows for the separation of the logical view of data from its physical representation.
There are two types of data independence:
- Physical Data Independence: It refers to the ability to modify the physical storage structures or devices without affecting the logical schema or application programs. This means that changes in the physical storage, such as adding or modifying storage devices, should not require any modifications to the way data is accessed or queried by the applications.
- Logical Data Independence: It refers to the ability to modify the logical schema or the way data is organized, without affecting the external schema or application programs. This means that changes in the logical structure of the data, such as adding or removing attributes or changing relationships between entities, should not require modifications to the application programs that access the data.
Data independence is an essential feature of modern database systems as it provides flexibility and simplifies the development and maintenance of applications. It allows for changes to be made at the physical or logical level without disrupting the functioning of the applications built on top of the database. This separation between the logical and physical layers also provides a level of abstraction, allowing developers to focus on the logical aspects of the data without being concerned about the underlying storage details.