# 使用
#### 语法格式
- 创建全量物化视图
  ```
  CREATE MATERIALIZED VIEW [ view_name ] AS { query_block };
  ```
  

- 全量刷新物化视图
  ```
  REFRESH MATERIALIZED VIEW [ view_name ];
  ```
  

- 删除物化视图
  ```
  DROP MATERIALIZED VIEW [ view_name ];
  ```
  

- 查询物化视图
  ```
  SELECT * FROM [ view_name ];
  ```
  
 
#### 示例
```
--准备数据。
openGauss=# CREATE TABLE t1(c1 int, c2 int);
openGauss=# INSERT INTO t1 VALUES(1, 1);
openGauss=# INSERT INTO t1 VALUES(2, 2);
--创建全量物化视图。
openGauss=# CREATE MATERIALIZED VIEW mv AS select count(*) from t1;
CREATE MATERIALIZED VIEW
--查询物化视图结果。
openGauss=# SELECT * FROM mv;
 count 
-------
     2
(1 row)
--向物化视图中基表插入数据。
openGauss=# INSERT INTO t1 VALUES(3, 3);
INSERT 0 1
--对全量物化视图做全量刷新。
openGauss=# REFRESH MATERIALIZED VIEW mv;
REFRESH MATERIALIZED VIEW
--查询物化视图结果。
openGauss=# SELECT * FROM mv;
 count 
-------
     3
(1 row)
--删除物化视图。
openGauss=# DROP MATERIALIZED VIEW mv;
DROP MATERIALIZED VIEW
```