How to Use PostgreSQL Materialized Views

How it works.

1. First, specify the view_name after the CREATE MATERIALIZED VIEW clause.
2. Second, add the query that gets data from the underlying tables after the AS keyword.
3. Third, if you want to load data into the materialized view at the creation time, use the WITH DATA option; otherwise, you use WITH NO DATA .

1. How do materialized views work in Postgres?
2. What is PostgreSQL materialized view?
3. How does a materialized view work?
4. Where is materialized view used?
5. Does PostgreSQL cache views?
6. Does PostgreSQL have materialized views?
7. Why use materialized view instead of a table?
8. Can we delete data from materialized view?
9. How do you refresh a materialized view?

How do materialized views work in Postgres?

Materialized views in PostgreSQL use the rule system like views do, but persist the results in a table-like form. ... When a materialized view is referenced in a query, the data is returned directly from the materialized view, like from a table; the rule is only used for populating the materialized view.

What is PostgreSQL materialized view?

Materialized views are disc-stored views that can be refreshed. Like views, they are defined by a database query. Unlike views, their underlying query is not executed every time you access them. Creating a materialized view is pretty simple: SQL.

How does a materialized view work?

A materialized view in Oracle is a database object that contains the results of a query. They are local copies of data located remotely, or are used to create summary tables based on aggregations of a table's data. ... You can select data from a materialized view as you would from a table or view.

Where is materialized view used?

You can use materialized views to increase the speed of queries on very large databases. Queries to large databases often involve joins between tables, aggregations such as SUM , or both. These operations are expensive in terms of time and processing power.

Does PostgreSQL cache views?

No. A view is basically a macro - your view definition gets merged with the query against it and then executed.

Does PostgreSQL have materialized views?

PostgreSQL extends the view concept to the next level that allows views to store data physically. And these views are called materialized views. Materialized views cache the result of a complex and expensive query and allow you to refresh this result periodically.

Why use materialized view instead of a table?

Basically views are exist logically unlike tables. ... Materialized views are physically exist in database. Whenever the base table is updated the Materialized view gets updated. Materialized views are updated periodically based upon the query definition, table can not do this.

Can we delete data from materialized view?

You cannot delete rows from a read-only materialized view. If you delete rows from a writable materialized view, then the database removes the rows from the underlying container table. However, the deletions are overwritten at the next refresh operation.

How do you refresh a materialized view?

To update the data in a materialized view, you can use the REFRESH MATERIALIZED VIEW statement at any time. When you use this statement, Amazon Redshift identifies changes that have taken place in the base table or tables, and then applies those changes to the materialized view.