Logical vs. Physical Modeling

by Kathy S
The two authors of this article start off by declaring that data modeling serves as a link between business needs and system requirements. They stress that if we are going to work with databases, it is important to understand the difference between logical and physical modeling, and how they relate to each other. First, Logical Modeling deals with gathering business requirements and converting those requirements into a model. Also, it involves gathering information about business processes, business entities, and organizational units. After, diagrams and reports are produced (entity relationship , business process, and process flow diagrams). According to the authors, it’s important to note that logical modeling affects the direction of database design and indirectly affects the performance and administration of an implemented database. More options become available when time is invested performing logical modeling. Next, the authors go into Physical modeling. Physical modeling involves the actual design of the database according to the requirements that were established during logical modeling. Physical modeling deals with the conversion of the logical, or business model, into a relational database model. During physical modeling, objects are created based on everything that was defined during logical modeling. Other objects like indexes and snapshots can be defined during physical modeling. Physical modeling is when all the pieces come together to complete the process of defining a database for a business. The authors conclude that the importance of understanding the difference between logical and physical modeling helps us to build better organized and more effective database systems.

In week 4 and this past week (week 5)  we learned about both Logical and Physical Database Design. This article definitely relates to the topic for this past week. The purpose of Physical database design is to translate the logical description of data into the technical specifications for storing and retrieving data. The primary goal of physical database design is data processing efficiency.

I liked the article, but at the same time I didn’t because it didn’t go into more detail about both logical and physical database design. The article is very basic and general and is helpful to those who have no clue about database design. The textbook is much more specific, and learned more there. Regardless, I would still recommend to read this article to those that want a basic overview what the difference between logical and physical modeling are.

Ryan K. Stephens and Ronald R. Plew. (2011, March). Logical Versus Physical Database Modeling. Developer.com. Retrieved October 27, 2012, from http://www.developer.com/tech/article.php/641521/Logical-Versus-Physical-Database-Modeling.htm

3 thoughts on “Logical vs. Physical Modeling

  • October 28, 2012 at 9:10 pm

    It’s very important to understanding the business requirements before creating the logical model. It’s also as important to have a flawless and fixed logical model before implementing that into a physical model. For people who want to become data warehouse architects, the article is a great source to learn and understand the importance of each step that leads up to the final physical infrastructure. Thank you for sharing.

  • October 29, 2012 at 12:30 am

    Thanks for sharing this article as it clarifies the differences between logical and physical design even though the textbook is more in depth. Throughout the course of our blogs I do notice that many of these articles stress the importance in accurately obtaining business processes and rules, so the logical modeling of a database can be detrimental if not captured by the physical modeling phase.

  • October 29, 2012 at 10:37 am

    I really like this article. It doesn’t thoroughly go into detail of logical and physical modeling but it did do a good job in distinguishing the two. Physical modeling is done by creating objects from the logical data. The physical data model is used for retrieving and storing data. However, without the logical data model, we would not be able to create a physical model. Good job in picking in this article to blog on, Kathy.

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