Data Independence Types in DBMS:
Definition and Explanation:
The separation of data descriptions from the application programs (or
user-interfaces) that uses the data is called 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
features of DBMS.
The three-level architecture provides the concept
of data independence, which means that upper-levels are unaffected by changes to
lower-levels. The three-level architecture makes it easier to achieve true data
Types of Data Independence:
(i) Logical data independence
(ii) Physical data independence
(i) Logical Data Independence:
Logical data independence is the capacity to change the conceptual schema
without having to change external schemas or application programs. Changes in
the conceptual schema may include addition or removal of entities, attributes or
relationships and should be possible without having to change existing external
views or having to rewrite application programs.
(ii) Physical Data Independence:
Physical data independence is the capacity to change the internal schema without
having to change the conceptual schemas 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 organizations or storage structures.
- Modifying indexes.
The above-mentioned changes should be possible without having to change the
conceptual or external schemas.