Differences Between Views and Materialized Views in SQL

When working with databases, views and materialized views are important tools for managing data effectively. Both have their unique characteristics, advantages and use cases. Understanding the differences can help us choose the best option for our requirements.

In this article, we will cover detailed explanations, practical examples, clear outputs and key differences between view and materialized view for better understanding.

Key Differences Between Views and Materialized Views

Following are the differences between the view and table:

What is a View in SQL?

A View is a virtual relation that acts as an actual relation. It is not a part of logical relational model of the database system. It is a virtual table created by a SQL query. It dynamically fetches data from the underlying tables whenever accessed, without storing the data physically in the database.

Characteristics of Views

• Dynamic Execution: Data is generated each time the view is accessed.
• No Physical Storage: Views only store the query definition.
• No Storage or Update Cost: Since no data is stored, no additional costs are involved.
• Use Cases: Useful for simplifying complex queries, enhancing data security, and creating a logical layer for specific users.

Syntax

CREATE VIEW view_name AS  
SELECT column1, column2, ...  
FROM table_name  
WHERE condition;

What is a Materialized View in SQL?

A materialized view stores the result of a query physically in the database. It can be refreshed manually or automatically to reflect updates in the underlying tables. The process of keeping the materialized views updated is known as view maintenance. Database system uses one of the three ways to keep the materialized view updated:

• Update the materialized view as soon as the relation on which it is defined is updated.
• Update the materialized view every time the view is accessed.
• Update the materialized view periodically.

Characteristics of Materialized Views

• Physical Storage: Stores query results for faster data retrieval.
• Refresh Options: Can be refreshed immediately, on-demand, or periodically.
• Performance Benefits: Improves query performance for frequently accessed or large datasets.
• Storage and Update Costs: Requires additional space and incurs overhead for maintaining data consistency.

Syntax

CREATE MATERIALIZED VIEW materialized_view_name  
BUILD [IMMEDIATE | DEFERRED]  
REFRESH [FAST | COMPLETE | FORCE]  
ON [COMMIT | DEMAND]  
AS  
SELECT column1, column2, ...  
FROM table_name  
WHERE condition;

Conclusion

Both views and materialized views are powerful tools in SQL for managing and optimizing data. While views are ideal for creating dynamic, virtual tables for occasional use, materialized views are better suited for scenarios requiring frequent access to precomputed results. By understanding their differences and use cases, we can improve our database design and performance.