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Structure Independence

Structure Independence is a previously uncharacterized database property akin to physical and logical data independence.

Physical data independence divorces the storage of data from its logical representation, maximizing the ability to tune and evolve the physical storage of data without affecting existing applications. Logical data independence divorces the underlying logical representation from the many different views presented to applications or users, maximizing the ability to customize the presentation of information for purposes of convenience or security.[Hellerstein 1999].

Structure independence divorces structure representation from object representation. It eliminates unnecessary resource competition between structure-only and object-only transactions and it reduces the cost and disruption resulting from database schema changes.

Definition: A database schema is structure independent if and only if it consists exclusively of object relations containing only attribute data (i.e., no foreign keys) and structure relations containing only foreign keys (i.e., no attribute data).
REQUEST FOR INPUT: In 2004, I submitted a paper on the Aggregate-Link representation that was rejected. The Reviewer noted:
"... 'structure independence' is an interesting concept. The concept itself is probably known in various guises, but I haven't seen it articulated before."

We would appreciate hearing from anyone who has seen this distinction between the Primary Key / Foreign Key and Junction Table representations addressed in a publication. Thanks.

Page Content first published: November 13, 2007
Page Content last updated: November 13, 2007