Materialised View vs. View

Attribute	Materialised View	View
Definition	A physical copy of the data that is stored on disk	A virtual table that is generated based on a query
Storage	Requires storage space on disk	Does not require additional storage space
Performance	Improved performance for read-heavy workloads	May have slower performance compared to materialised views
Updates	Needs to be refreshed periodically to reflect changes in the base data	Automatically reflects changes in the base data

Introduction

Materialised views and views are both database objects that store queries for easy access and retrieval of data. While they serve similar purposes, there are key differences between the two that make them suitable for different use cases.

Definition

A view in a database is a virtual table that is based on the result set of a SELECT query. It does not store any data itself but provides a way to present data from one or more tables in a structured format. On the other hand, a materialised view is a physical copy of the result set of a query that is stored in the database. This means that the data in a materialised view is precomputed and stored, making it faster to access.

Performance

One of the key differences between materialised views and views is their impact on performance. Views are dynamic and do not store any data, so every time a view is queried, the underlying query is executed to retrieve the data. This can result in slower performance, especially for complex queries or large datasets. Materialised views, on the other hand, store precomputed data, which means that querying a materialised view is faster as the data is already available.

Storage

Views do not consume any additional storage space in the database as they do not store any data themselves. They simply provide a way to access data from existing tables. Materialised views, on the other hand, store a physical copy of the data, which means they require storage space in the database. This can be a consideration when working with large datasets or limited storage capacity.

Refresh

Another key difference between materialised views and views is how they are updated. Views always reflect the current data in the underlying tables, as they do not store any data themselves. This means that every time a view is queried, it retrieves the most up-to-date data. Materialised views, on the other hand, need to be refreshed periodically to update the data they store. This can be done manually or automatically based on a schedule.

Usage

Views are commonly used for simplifying complex queries, providing a layer of abstraction over the underlying tables, and controlling access to data by restricting the columns or rows that can be queried. Materialised views, on the other hand, are used when performance is a priority, such as for frequently accessed reports or dashboards that require fast retrieval of data. They can also be used for offline analysis or data warehousing.

Conclusion

In conclusion, materialised views and views are both valuable tools in a database environment, each with its own strengths and weaknesses. Views are dynamic and do not store data, making them suitable for simplifying queries and controlling access to data. Materialised views, on the other hand, store precomputed data for faster access, making them ideal for performance-critical applications. Understanding the differences between the two can help in choosing the right tool for the job.