Complete-refresh Materialized View ​

Overview ​

Complete-refresh materialized views can be fully refreshed only. The syntax for creating a complete-refresh materialized view is similar to the CREATE TABLE AS syntax.

Usage ​

Syntax ​

• Create a complete-refresh materialized view.

  CREATE MATERIALIZED VIEW [ view_name ] AS { query_block };

• Fully refresh a materialized view.

  REFRESH MATERIALIZED VIEW [ view_name ];

• Delete a materialized view.

  DROP MATERIALIZED VIEW [ view_name ];

• Query a materialized view.

  SELECT * FROM [ view_name ];

Examples ​

-- Prepare data.
openGauss=# CREATE TABLE t1(c1 int, c2 int);
openGauss=# INSERT INTO t1 VALUES(1, 1);
openGauss=# INSERT INTO t1 VALUES(2, 2);

-- Create a complete-refresh materialized view.
openGauss=# CREATE MATERIALIZED VIEW mv AS select count(*) from t1;
CREATE MATERIALIZED VIEW

-- Query the materialized view result.
openGauss=# SELECT * FROM mv;
 count 
-------
     2
(1 row)

-- Insert data into the base table in the materialized view.
openGauss=# INSERT INTO t1 VALUES(3, 3);
INSERT 0 1

-- Fully refresh the complete-refresh materialized view.
openGauss=# REFRESH MATERIALIZED VIEW mv;
REFRESH MATERIALIZED VIEW

-- Query the materialized view result.
openGauss=# SELECT * FROM mv;
 count 
-------
     3
(1 row)

-- Delete the materialized view.
openGauss=# DROP MATERIALIZED VIEW mv;
DROP MATERIALIZED VIEW

Support and Constraints ​

Supported Scenarios ​

• Supports the same query scope as the CREATE TABLE AS statement does.
• Supports index creation in complete-refresh materialized views.
• Supports ANALYZE and EXPLAIN.

Unsupported Scenarios ​

Materialized views cannot be added, deleted, or modified. They support only query statements.

Constraints ​

When a complete-refresh materialized view is refreshed or deleted, a high-level lock is added to the base table. If the definition of a materialized view involves multiple tables, pay attention to the service logic to avoid deadlock.