Data Independence - Data Independence Types

Data Independence Types

Data independence has two types. They are:

  1. Physical Independence
  2. Logical Independence.

Data independence can be explained as follows: Each higher level of the data architecture is immune to changes of the next lower level of the architecture.

Physical Independence: The logical scheme stays unchanged even though the storage space or type of some data is changed for reasons of optimisation or reorganisation. In this external schema does not change. In this internal schema changes may be required due to some physical schema were reorganized here. Physical data independence is present in most databases and file environment in which hardware storage of encoding, exact location of data on disk,merging of records, so on this are hidden from user.

Logical Independence: The external scheme may stay unchanged for most changes of the logical scheme. This is especially desirable as the application software does not need to be modified or newly translated.

Read more about this topic:  Data Independence

Famous quotes containing the words data, independence and/or types:

    “This city is neither a jungle nor the moon.... In long shot: a cosmic smudge, a conglomerate of bleeding energies. Close up, it is a fairly legible printed circuit, a transistorized labyrinth of beastly tracks, a data bank for asthmatic voice-prints.”
    —Susan Sontag (b. 1933)

    “The subject of the novel is reality liberated from soul. The reader in complete independence presented with a structured process: let him evaluate it, not the author. The façade of the novel cannot be other than stone or steel, flashing electrically or dark, but silent.”
    —Alfred Döblin (1878–1957)

    “Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
    —Talcott Parsons (1902–1979)