DBMS Notes

Data Independence

As we know Basic purpose of 3-level schema is to achieve the goal of, data Independence.

Data independence means, independent the data from user. Therefore, It follows the 3-level of abstraction (3-schema architecture).

Types of Data Independence

There are two basic types of data independence, As explain below

1. Logical Data Independence

  • Logical data independence separates the external level from the logical/conceptual level.
  • If any change is occur at conceptual schema then it will not affect the user view.

2. Physical Data Independence

Physical data independence separates the physical level (internal) from the conceptual view.

 In the same way, if any change is require in physical schema then it will not affect the conceptual schema.

i.e Gmail makes changes in conceptual and physical schema at regular basis without changing the user view.

Note: Data can store centralize or distributed in database storage.

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