What are materialized views in databases and how do they differ from regular ones?

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Materialized views are special database objects that store the results of complex SQL query execution physically on disk as a separate table. Unlike regular views, which recalculate data based on base tables upon every access, materialized views return the ready-made result instantly. This makes them an indispensable tool for optimizing analytical queries, reports, and heavy aggregations that take too long to run in real time.

The main drawback of materialized views is the issue of data relevance. Since they store a static snapshot of the results at the time of their last refresh, any changes in the base tables are not reflected in the view automatically. Because of this, developers have to set up a schedule for periodic data updates or run synchronization manually after completing large batch data loading operations.

For the effective use of materialized views in practice, it is recommended to follow certain rules.

1. Analyze the frequency of data reading and writing to ensure the feasibility of creating a physical copy of the results.
2. Set up incremental updates where supported by the DBMS so as not to recalculate the entire volume of data from scratch.
3. Add indexes directly to the materialized view to further speed up searches by ready-made aggregates.
4. Monitor disk space usage, as data duplication can lead to rapid disk overflow.

As a result, this tool is well-suited for OLAP systems, data warehouses, and dashboards where a slight delay in information relevance is acceptable for the sake of instant interface response.

What are materialized views in databases and how do they differ from regular ones?

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