DBMS Data Independence

Data Independence

Data independence is ability to modify a schema definition in one level without affecting a schema definition in the next higher level.

There are two levels of data independence:

  1. Physical Data Independence
  2. Logical Data Independence

These are described below:

1. Physical Data Independence:

  • Physical Data Independence is the ability to modify the physical schema without requiring any change in application programs.
  • Modifications at the internal levels are occasionally necessary to improve performance. possible modifications at internal levels are change in file structures, compression techniques, hashing algorithms, storage devices, etc.
  • Physical data independence separates conceptual levels from the internal levels.
  • This allows to provide a logical description of the database without the need to specify physical structures.
  • Comparatively, it is easy to achieve physical data independence.

2. Logical Data Independence:

  • Logical data independence is ability to modify the conceptual schema without requiring any change in application programs.
  • Modification at the logical levels are necessary whenever the logical structures of the database is altered.
  • Logical data independence separates external level from the conceptual view.
  • Comparatively it is difficult to achieve logical data independence.
  • Application programs are heavily dependent on logical structures of the data they access.so any change in logical structure also requires programs to change.



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Questions


Diksha agarwal | 08-Mar-2017 11:38:36 pm

Is data indepence also called data abstraction and is it also have another level called view level and if it have then what it is ??


Abor | 20-Sep-2017 02:17:44 pm

how does database approach overcomes limitations of file storage of data


ubaid sayyed | 01-Nov-2017 08:11:19 pm

what is schema


Gift Kuwandira | 29-Aug-2018 10:43:28 pm

Describe each of the three levels of the ANSI-SPARC architecture


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