What's the difference between a physical and a logical data structure?

A physical data structure refers to the actual organisation of data in memory, while a logical data structure is the abstract representation of data.

A physical data structure, also known as a storage structure, is concerned with the actual arrangement of data in a computer's memory. It deals with how the data is stored and accessed in the hardware, and is closely linked to the operating system and the file structures used. Physical data structures are often implemented as arrays, linked lists, stacks, queues, trees, and graphs. The choice of physical data structure can significantly impact the efficiency of data access and manipulation, as different structures have different strengths and weaknesses in terms of memory usage and processing speed.

On the other hand, a logical data structure, also known as a data model, is an abstract representation of data, independent of how it is physically stored. It focuses on how users interact with data and how data is related to other data. Logical data structures are often represented as tables, graphs, trees, or other high-level models. They provide a way to organise and manipulate data that is intuitive and convenient for the user, without requiring them to understand the underlying physical data structure.

For example, a database might use a logical data structure such as a relational model, where data is organised into tables with rows and columns. However, the physical data structure used to store this data on disk might be a B-tree or a hash table, which are more efficient for data retrieval and storage. To deepen your understanding of how data is structured within databases, explore the concept of database models and their characteristics.

Additionally, to see how logical structures like trees function in computer algorithms, the page on logical operations in trees provides detailed insights.

If you're interested in a broader perspective on how data is conceptualised and used in information systems, the notes on understanding data and databases might prove valuable.

A-Level Computer Science Tutor Summary: In simple terms, a physical data structure is about how data is actually organised in a computer's memory, like where it's stored. A logical data structure is more about the idea or way we see and use the data, like how we arrange it in our minds or in programs. Both are important for making data easy to use and efficient to manage.