The main difference between logical and physical data model is that logical data model helps to define the data elements and their relationships, while physical data model helps to design the actual database based on the requirements gathered during the logical data modelling.
Generally, it is necessary to model data before storing them to the database. Therefore, data modelling is the process of creating a data model for the data to be stored in a database. It represents the data objects and the association between those objects. A data model provides a wide range of advantages. It helps to define the table structure and keys such as primary key and foreign keys on the tables. Creating a data model at the initial state helps to reduce the development time and the cost. Moreover, the database developers can easily create the real database easily using the models. In overall, there are different types of models, and two of them are logical data model and physical data model.
Key Areas Covered
1. What is a Logical Data Model
-Definition, Functionality
2. What is a Physical Data Model
-Definition, Functionality
3. Difference Between Logical and Physical Data Model
-Comparison of Key Differences
Key Terms
Database, Data Models, Logical Data Model, Physical Data Model
What is a Logical Data Model
After obtaining the business requirements, the logical model describes the data to a great extent, but it does not take part in implementing the database. In other words, it is the basis for developing the physical model. It includes all the entities, relationships between them and the attributes of the entities. Generally, the logical data model can be designed and developed independently from the DBMS. Moreover, it is possible to apply normalization. Usually, it is up to the third normal form (3NF).
What is a Physical Data Model
A physical data model is a model that helps to implement the database. In other words, it represents the way of building the database. Moreover, the physical data model gives an abstraction of the database and helps to generate the schema.
It helps to model the database column keys, constraints, indexes, triggers and other RDBMS features. It also converts the entities into tables, relationships into foreign keys and attributes into columns. Furthermore, it is possible to modify the physical data model based on physical constraints or requirements.
Difference Between Logical and Physical Data Model
Definition
A logical data model is a model that describes data as much as possible, without regard to how they will be physically implemented in the database. In contrast, a physical data model is a model that represents how the actual database is built. Hence, this is the main difference between logical and physical data model.
Basis
Another difference between logical and physical data model is that the logical data models define the data elements and their relationships, while the physical data models allow developing the actual database.
Created By
Data architects and business analysts create logical data models, whereas database administrators and developers create physical data models.
Objective
Besides, the objective of a logical data model is to develop a technical map of rules and data structures. On the other hand, the objective of a physical model is to implement the actual database. Thus, this is an important difference between logical and physical data model.
Complexity
Moreover, physical data models are more complex than logical data models.
Conclusion
In brief, there are three types of data models in database designing. Two of them are logical and physical data model. The main difference between Logical and Physical Data Model is that Logical data models help to define the data elements and their relationships, while the physical data models help to design the actual database based on the requirements gathered during the logical data modelling.
References:
1.Logical Data Model, Available here.
2.Physical Data Model, Available here.
3.“Conceptual, Logical and Physical Data Model.” Visual Paradigm, Available here.
4.“What Is Data Modelling? Conceptual, Logical, & Physical Data Models.” Meet Guru99 – Free Training Tutorials & Video for IT Courses, Available here.
Image Courtesy:
1.”The example series icon: A simple flat file” By Xiong (talk) (Uploads) – Own work (CC BY-SA 3.0) via Commons Wikimedia
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