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Advantages and Disadvantages of an ER-Model

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Pre-requisites: ER Model

Entity is a thing or an object in real world. As the name suggests that Entity Relationship model uses collection of basic objects called entities & relationships.It develops a very simple and easy to design view of data. Entity relationship model is widely used in Database design. To get some clarity about an ER-Model look at the following example:

ENTITY RELATIONSHIP MODEL

 

From the above example we can see the relationship WORK_FOR is between entities EMPLOYEE and DEPARTMENT. It is a sample diagram as the original diagram includes many entities and relationships. 

Advantages

  1. SIMPLE :  It is simple to draw an ER diagram when we know entities and relationships. 
  2. EFFECTIVE : It is an effective communication tool.
  3. EASY TO UNDERSTAND : The design of ER is very logical and hence they are easy  to design and understand.They show database capabilities like how tables, keys and columns are used to find a solution to the given question.
  4. INTEGRATED :  The ER Model can be easily integrated with relational model.
  5. USEFUL IN DECISION MAKING : Since some of the entities in the database are analyzed by an ER-Diagram, So by drawing an ER-Diagram we come to know what kind of attributes and relationship exist between them.
  6. EASY CONVERTION : It can be easily converted to other type of models. 
  7. DATABASE TROUBLESHOOTING : ER diagrams are used to analyze existing databases to find and resolve the key issues in logic or deployment. Drawing the diagram should reveal where it’s going wrong.
  8. FLEXIBLE: ER models are flexible and can be modified easily to accommodate changes in the database design or structure.
  9. MINIMIZES DATA REDUNDANCY: ER models help minimize data redundancy by identifying and eliminating duplicate data entries.
  10. SCALABILITY: ER models can be used for databases of varying sizes, from small to large.
  11. VISUAL REPRESENTATION: ER models provide a visual representation of the database structure, making it easier for stakeholders to understand and provide feedback.
  12. DOCUMENTATION: ER models provide useful documentation for future reference, making it easier to maintain and update the database in the long run.

Disadvantages

  1.  LOSS OF INFORMATION:  While drawing an ER Model some of the information can be hidden or lost.
  2. LIMITED RELATIONSHIP: ER model can represent limited relationships as compared to other models and It is not possible to indicate  primary keys and foreign keys when they’re expected.
  3. NO REPRESENTATION FOR DATA MANIPULATION: It is not possible to represent data manipulation(commands like insert(),delete(),alter(),update()) in ER model.
  4. NO INDUSTRY STANDARD: There is no industry standard for notations of an ER diagram. 
  5. DATA INCONSISTENCY: Due to improper Normalization some data inconsistency may occur so, while creating an ER diagram at least it should be in third normal form. 
  6. MISSING CARDINALITIES: Missing relationship cardinalities, so everything looks like a one-to-one relationship. One-to-one relationships are actually quite rare.
  7. DIFFICULT TO MODIFY: ER models can be difficult to modify once they are created. Any changes made to the model may require extensive rework, which can be time-consuming and expensive.
  8. LIMITED ATTRIBUTE REPRESENTATION: ER models may not be able to represent all the attributes required for a particular problem domain. This can lead to either the loss of important data or the creation of a complex and unwieldy model.
  9. LACK OF SUPPORT FOR BUSINESS RULES: ER models do not provide support for business rules, which can make it difficult to ensure data integrity and enforce constraints.
  10. DIFFICULT TO SCALE: ER models can be difficult to scale to accommodate larger data sets. As the amount of data in the database grows, the ER model may need to be modified to handle the increased complexity.
  11. DEPENDENCE ON USER UNDERSTANDING: ER models rely heavily on the understanding of the user to correctly identify the entities and relationships. If the user does not have a good understanding of the problem domain, the resulting ER model may not accurately represent the data.
  12. LIMITED SUPPORT FOR ABSTRACTION: ER models are not designed to support abstraction, which can make it difficult to represent complex relationships or data structures in a simple and intuitive way.

Last Updated : 09 May, 2023
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