Data Modeling is too subjective.

by Shigom H
Data modeling is a lengthy process for designers that involves a thorough analysis of the business requirements, and entity relationships. Most of this is done during the conceptual data modeling phase, in which a simple diagram(Entity Relationship Diagram) illustrates the relationships between the main entities of the business. In the “Necessity of Conceptual Data Modeling for Information Quality“ Pete Stiglich points out some typical problems that occur in conceptual data modeling and the approach that designers must take to create a more realistic model. The author describes a conceptual data model as the “picture on the puzzle box” that outlines what the “information puzzle” (Logical, Physical Model) should look like. Therefore, a lot of thought must go into the conceptual data model to avoid potential problems when developing the final product.

In class we talked about entity relationship diagrams, but failed to visit the relationship between entities from a “historical, longitudinal perspective” as highlighted by the author. For example, the relationship between a Store and Employee would be considered a one-to-many relationship. However, if the store expands and an employee may alternate between stores, then the relationship may also be many-to-many. It is important that the entity relationship diagram is modeled with the future in mind so that the system can serve its purpose.

Failure to accurately portray relationships between entities in the initial phase, can increase costs in the final development of the system . The article talks about a pet supply company that mistakenly identified the relationship between customer and pet as a one- to-many relationship. Since each member of that customer’s family could also be identified as an owner . As a result, a new pet record had to be created each time a random person brought that pet in for services. This translated to a “loss of confidence by the business in this system” because now they have pointless duplicate data.

Constructing the entity relationship diagram may be considered a simple task, and it’s subjective in nature, often relying on business assumptions. I enjoyed the article because it talked about the importance of identifying relationships early on, so that new ones want be discovered when the system is being implemented. The article also provided different solutions to similar problems that we went over in class.

Stiglich, P., & EWSolutions. (n.d.). Necessity of Conceptual Data Modeling for Information Quality. InfoAdvisors – Project, Process, and Data Management > Home. Retrieved October 15, 2012, from http://www.infoadvisors.com/ArticlesVideos/ConceptualDataModelingforInformationQuality.aspx

3 thoughts on “Data Modeling is too subjective.

  • October 15, 2012 at 12:12 am
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    The examples provided are helpful in reinforcing good practices and what to look out for when designing a database. Understanding the organization’s current business rules and requirements is of great importance, however thinking ahead and designing for the future can save modelers from headaches and ensures the system can support the growth and changes of the organization. The “picture on the puzzle box” example was insightful.

  • October 15, 2012 at 12:13 am
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    Great Post, Constructing the entity relationship diagram may be considered a simple task, but it should always be handled carefully and correctly. Imagine if we messed up something between the entity relationship then it will definitely affect the final development of the system.

  • October 15, 2012 at 12:18 am
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    This article is somewhat similar to the article I chose. Both articles emphasize on how important it is to keep in mind of the future changes a data model can have because in the long run it will cause problems. This article emphasizes on the relationships between entities, and my article emphasized on the definition of the entity. Both are very important.

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