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Conceptual, logical and physical schemas

Posted by jyothsnav 2471 days ago (Editorial)

A data model instance may be one of 3 kinds:


Conceptual Schema: describes the semantics of a domain, being the scope of the model. For example, it may be a model of the interest area of an organization or industry. This consists of entity classes, representing kinds of things of significance in the domain, and relationships assertions about associations between pairs of entity classes. A conceptual schema specifies the kinds of facts or propositions that can be expressed using the model. In that sense, it defines the allowed expressions in an artificial 'language' with a scope that is limited by the scope of the model.


Logical Schema: describes the structure of some domain of information. This consists of descriptions of tables and columns, object oriented classes, and XML tags, among other things.


Physical Schema: describes the physical means by which data are stored. This is concerned with partitions, CPUs, tablespaces, and the like.





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