Logical versus Physical Design

Posted by Sudheer Sharma 21 January 2009

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After all business requirements have been gathered for a proposed database, they must be modeled. Basically, data modeling act like a bridge between business needs and system requirements

Two types of data modeling are as follows:

Logical Modeling
Physical Modeling

Logical Modeling

It involves gathering information about business processes, entities, attributes for each entity and relationship among the entities. The deliverables of logical modeling include E-R(Entity – Relationship) diagrams, Business Process diagrams. This model is highly normalized.

ERD is to provide the development team with a picture of the different categories of data for the business, and how these entities are realted to one another.

BPD gives the development team an idea of how data moves within the organization.

Physical Modeling

It involves actual design of the database according to the requirements that were established during logical modeling. It deals with the conversion of logical or business model, into a relational data model.

It involves gathering the schema for tables, indexes, default and check constraints, and views for the application. This model include data types for each attribute and can be normalized or de-normalized.

Conclusion

Understanding the difference between logical and phyical modeling will help you build better organized and more effective database systems.

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