Creating and Using Materialized Views in PostgreSQL (Improving Query Performance)

Materialized views are a high-performance query technique in PostgreSQL that can significantly improve performance for large tables or complex queries.

What is a Materialized View?

A materialized view is a special type of view that stores pre-calculated and required data, making it immediately available when needed. This technology reduces unnecessary computation and interaction, thereby significantly improving performance on large tables or complex queries.

Why Materialized Views?

Materialized views can significantly improve the following scenarios:

• Large Tables: For large tables, materialized views reduce access to underlying tables and do not require storing the entire table in advance.
• Complex Queries: Complex queries can be optimized and simplified using materialized views.

Creating Materialized Views

Create a materialized view using the CREATE MATERIALIZED VIEW statement

CREATE MATERIALIZED VIEW mv_name AS 
SELECT * FROM original_table;

Use clauses in create materialized view for complex queries

CREATE MATERIALIZED VIEW mv_name AS 
WITH subquery AS (
    SELECT column1, column2 FROM original_table WHERE condition = 'value'
) 
SELECT column1, column2 FROM subquery;

Trigger updates to a materialized view using triggers

CREATE OR REPLACE FUNCTION update_mview() RETURNS TRIGGER AS $$
BEGIN
    INSERT INTO mv_name (column1, column2)
    VALUES (NEW.column1, NEW.column2);
    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER trig_update_mview 
BEFORE INSERT ON original_table 
FOR EACH ROW EXECUTE PROCEDURE update_mview();

Using Materialized Views

Execute a query on the materialized view directly

SELECT * FROM mv_name;

Use a materialized view to optimize complex queries

SELECT * FROM mv_name WHERE condition = 'value';

Delete a materialized view

DROP MATERIALIZED VIEW mv_name;

Summary

Materialized views are a high-performance query technique in PostgreSQL that can significantly improve performance for large tables or complex queries. By pre-calculating and storing required data, materialized views reduce unnecessary computation and interaction, thereby improving query performance.