Materialized View in BigQuery: Definition and Usage

A materialized view in BigQuery is a precomputed, stored result of a query that updates automatically when the source data changes. It helps speed up query performance by avoiding repeated computation of complex queries.

How It Works

Imagine you have a recipe you use often, and instead of cooking it from scratch every time, you prepare it once and keep it ready in the fridge. A materialized view works similarly in BigQuery. It stores the results of a query so that when you ask for the same data again, BigQuery can give you the stored results instantly instead of recalculating everything.

Behind the scenes, BigQuery automatically updates this stored data whenever the original tables change, so the materialized view stays fresh. This means you get faster query responses without worrying about outdated information.

Example

This example creates a materialized view that calculates the total sales per product from a sales table.

sql

CREATE MATERIALIZED VIEW `project.dataset.sales_summary` AS
SELECT product_id, SUM(amount) AS total_sales
FROM `project.dataset.sales`
GROUP BY product_id;

Output

Materialized view 'sales_summary' created successfully.

When to Use

Use materialized views when you have queries that run often and take a long time because they process large amounts of data or complex calculations. They are great for dashboards, reports, or any situation where you need quick access to summarized or aggregated data.

For example, if you have a daily sales report that sums up sales by product, a materialized view can keep this summary ready and updated, so your report loads instantly without waiting for BigQuery to recalculate everything each time.

Key Points

• Materialized views store query results physically for faster access.
• They update automatically when source data changes.
• They improve performance for repeated, complex queries.
• They are best for aggregated or summarized data used frequently.

Key Takeaways

Materialized views store precomputed query results to speed up repeated queries.

BigQuery automatically refreshes materialized views when source data changes.

Use materialized views for frequent, complex queries like reports and dashboards.

They reduce query cost by avoiding repeated full data scans.

Materialized views are ideal for summarized or aggregated data.