What Is Program Data Independence?


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Program data independence is a type of data transparency that refers to the immunity of changes made to users applications and their definition and organization of data. Program data independence matters for a database management system (DMS).

Physical data independence focuses on hiding details about the storage structure from user applications. As there is no difference in the operation that is carried out against the data, the user application should not be involved with these issues. The feature of data abstraction is found in the data independence and operation independence together. Within data independence there are two different levels; the first level and the second level.

  • First level of data independence
The first level is the schema definition. This is the logical structure of the data. A user application should not be affected when there are new additions made to the same relation when it is used on a subset of the attributes of a relation. The conceptual schema can be changed without having any effect on the current schema, as indicated by logical data independence.

  • Second level of data independence
This level is the physical data description, i.e. The physical structure of the data. The second level gives the ability to change the physical schema without changing the logical schema on the first level. For example, changing a file organization or storage structure is possible without making any changes to the external or conceptual schemas.

Each of the levels of program data independence is immune to changes made in the level below. These two levels, of logical and physical data independence, come together to form the general scope of program data independence as the ability to make data immune to the changes made to user applications. This includes changed made to the organization and definition of data.

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