What is Data Independence in Database
What is Data Independence in Database: The separation of data from the application programs or user interfaces that uses the data is known as Data Independence.Data independence also means that data can be updated/added in master tables without adding data into child tables. Data independence is one of the important feature of DBMS.
The three level architecture provide the concept of data independence in the data file of same organization, which means that the upper-levels are unaffected by changes to lower-levels of same file. The three level architecture makes it easier to achieve true data independency. There are two kinds of data independence.
- Logical data independence
- Physical data independence
Logical Data Independence
Logical data independence is the capacity to change the conceptual schema without having to change external schemas or application programs in the data file of the organization. Changes in the conceptual schema may include addition or removal of entities, attributes or relationships or tables and should be possible without having to change existing external view or having to rewrite application programs in the data file of organization.
Physical Data Independence
Physical data independence is the capacity to change the internal schema without having to change the conceptual schema or application programs. Changes in the internal schema may include
- Using new storage devices.
- Using different data structures.
- Switching from one access method to another.
- Using different file organization or storage structures.
- Modifying Indexes
The above mentioned changes should be possible without having to change the conceptual or external schema.