Wednesday, November 6, 2013

Logical vs. Physical view

The view of world depends on which lenses do you use and what you see!

Enterprise Architecture and its sub-domains always include different level of views, what’re differences between logical view and physical view?  Who are the audiences and how do they differ? What is the purpose of each?

A Logical view is concerned with the semantics of the elements, what do these 'things' represent; A Physical view is concerned with the both the semantics and syntax of the elements on how these 'things' are realized

A logical view is the view as presented to the end user. A logical view is as the customers or users see and understand it, and should be used to communicate with them.

The physical view is how and where the information reside. The physical view is a technical description of the implementation of the logical view. System development staff should: (a) communicate with actors in logical view and terms, and (b) translate agreed/approved logical view or changes to physical view correctly. 

A logical view focuses on functional requirements, or data modeling. Physical view does need to address quality requirements like resilience and availability. That is another difference between the two. 

From Database Management perspective: Logical view is at Entity and field level, including the kind of data (date, text, number). Natural keys are defined, and where not possible, artificial keys. Relationships include cardinality. Data quality elements are introduced as well, so some rules around when relationships are valid, or what states of entities are valid, are also included.

Physical View is at Entity and fields, including physical data types like VarChar. This will also include M->M relationship tables, index optimization, materialized views, etc. It may be denormalized to support performance as well. it may include database specific entitles used to protect data quality. 


Thank you for the details.
Your explanation of both logical and physical views are really clear. As I may suppose this structure may be applied to virtual data rooms described on virtual data room reviews.

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