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Views

  • PostgreSQL view is a logical table that represents data of one or more underlying tables through a SELECT statement.

  • A view does not store data physically except for a materialized view.

  • A view can be very useful in some cases such as:

  • A view helps simplify the complexity of a query because you can query a view, which is based on a complex query, using a simple SELECT statement.

  • Like a table, you can grant permission to users through a view that contains specific data that the users are authorized to see.

  • A view provides a consistent layer even the columns of underlying table changes.

  • Creating View in Postgresql:

CREATE VIEW view_name AS query;

  • Altering View

ALTER VIEW customer_master RENAME TO customer_info;

  • Dropping a view DROP VIEW IF EXISTS customer_info;

Materialized View

  • 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.

  • The materialized views are useful in many cases that require fast data access therefore they are often used in data warehouses and business intelligence applications.