Cantech Knowledge Base

Your Go-To Hosting Resource

  1. Linux
  2. How to Use Materialized Views in PostgreSQL?

How to Use Materialized Views in PostgreSQL?

Materialized views in PostgreSQL are an extremely powerful tool for optimizing query performance by maintaining the results of sophisticated queries in physical disk-based tables. Unlike regular views, which execute the query each time it is invoked, materialized views store the results and provide much faster data retrieval. This makes them highly well-suited for data warehousing and reporting, where performance is critical.

In this article, we will cover the application of materialized views in PostgreSQL, including how to create them, refresh strategies, as well as best practices. Whether you are a developer or a database administrator looking to optimize your queries, this tutorial will take you through how to get the most out of materialized views.

What are Materialized Views?

Materialized views are a physical mechanism for storing the result of a query, as opposed to the standard views, which execute the underlying query each time it is called. They are particularly useful when dealing with big data or joins with many tables. They can significantly speed up the performance of read-heavy applications and analytical queries.

Some key characteristics of materialized views in PostgreSQL are:

  • Stored physically on disk.
  • It must be manually updated to be up to date.
  • Perfect for working with big data.
  • Indexing to support performance improvements.

How to Create a Materialized View?

Creating a materialized view in PostgreSQL is very simple and can be done easily using the following command:

CREATE MATERIALIZED VIEW view_name AS
SELECT column1, column2, .
FROM table_name
WHERE conditions

For instance let’s say,

CREATE MATERIALIZED VIEW employee_salaries AS
SELECT employee_id, SUM(salary) AS total FROM employees

GROUP BY employee_id

This query creates a materialized view of employee_salaries, which stores the total salary for each employee.

Refreshing Materialized Views

Materialized views store data physically, which means the data in the materialized views will never be automatically refreshed when the data in the underlying tables changes.

REFRESH MATERIALIZED VIEW view_name

To avoid locking and allow for concurrent use, use the CONCURRENTLY keyword:

REFRESH MATERIALIZED VIEW CONCURRENTLY view

Note: A materialized view should have a unique index to use CONCURRENTLY.

Dropping Materialized View

To drop a materialized view, use the command DROP MATERIALIZED VIEW:

DROP MATERIALIZED VIEW view_name;

You can specify the IF EXISTS clause to avoid an error in case the view does not exist:

DROP MATERIALIZED VIEW if exists view_name

Benefits of Materialized Views

Some of the top benefits of materialized view!

  • Improved performance: Speeds up complex queries by maintaining results in physical stores.
  • Less Computation: Saves CPU time for repeated queries.
  • Indexing: Materialized views can be indexed for performance improvement.

Limitations of Materialized Views

  • Manual Refresh: Data can get outdated if it is not updated periodically.
  • Storage costs: Materialized views occupy physical disk space.
  • Concurrency Issues: Lock the view while refreshing it without using CONCURRENTLY.

Best Practices for Utilizing Materialized Views

Improve query performance through the use of indexes for materialized views.

  • Schedule Refreshs: Utilize cron jobs or the built-in job scheduler in PostgreSQL to automate the refresh process.
  • Monitor performance: Regularly monitor query performance and revise strategies.
  • Minimize Locking: Use refresh materialized view concurrently to minimize locking.

Conclusion

Materialized views are a powerful query performance optimization tool in PostgreSQL, particularly when dealing with complex data aggregations. By physically materializing the results, they greatly reduce query execution times. However, good refresh strategy management and indexing are necessary in order to guarantee performance and data consistency.
Leverage materialized views to increase your PostgreSQL applications’ speed while keeping the highest level of precision and efficiency.

Leverage materialized views to increase your PostgreSQL applications’ speed while keeping the highest level of precision and efficiency.

Frequently Asked Questions

Do materialized views get automatically refreshed?
No, PostgreSQL materialized views must be refreshed manually. The process can be automated by using scheduled jobs.

Can data in a materialized view be updated?

No, the data cannot be refreshed. The view should be refreshed to get the latest data from the underlying tables.

What is the difference between a view and a materialized view?
A regular view does not physically store data and always shows the latest data, while a materialized view stores the query results on disk and needs to be refreshed manually.

April 9, 2025