Data Independence

Data Independence

• Data independence is explained using the three-schema architecture.

• It is the characteristic of being able to modify the schema at one level of the database system without altering the schema at the next higher level.

Data Independence Classification

• Logical Data Independence

• Physical Data Independence

Logical Data Independence

• It is the capacity to change the conceptual schema without having to change the external schema.

• It separates the external level from the conceptual level.

• Any changes in the conceptual view of the data would not affect the user view of the data.

• Logical data independence occurs at the user interface level.

Physical Data Independence

• It is the capacity to change the internal schema without having to change the conceptual schema.

• Any changes in storage size of the database system server would not affect the conceptual structure of the database.

• It separates conceptual levels from the internal level.

• Physical data independence occurs at the logical interface level.