学习目标

掌握openGauss视图的管理：创建视图、删除视图、查询视图的信息、修改视图的信息。

课程作业

1.创建表，创建普通视图

newdb1=# CREATE TABLE tpcds.customer
newdb1-# (  c_customer_sk             integer,
newdb1(#   c_customer_id             char(5),
newdb1(#   c_first_name              char(6),
newdb1(#   c_last_name               char(8)
newdb1(# ) ;
CREATE TABLE
newdb1=# INSERT INTO tpcds.customer VALUES
newdb1-# (6885, 1, 'Joes', 'Hunter'),
newdb1-# (4321, 2, 'Lily','Carter'),
newdb1-# (9527, 3, 'James', 'Cook'),
newdb1-# (9500, 4, 'Lucy', 'Baker');
INSERT 0 4
newdb1=#
newdb1=#
newdb1=# CREATE VIEW tpcds.customer_details_view_v1 AS
newdb1-# SELECT * FROM tpcds.customer
newdb1-# WHERE c_customer_sk > 5400;
CREATE VIEW
newdb1=#
newdb1=# select * from tpcds.customer_details_view_v1;
 c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
          6885 | 1             | Joes         | Hunter
          9527 | 3             | James        | Cook
          9500 | 4             | Lucy         | Baker
(3 rows)
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2.使用视图创建新的视图

newdb1=# select * from tpcds.customer_details_view_v1;
 c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
          6885 | 1             | Joes         | Hunter
          9527 | 3             | James        | Cook
          9500 | 4             | Lucy         | Baker
(3 rows)

newdb1=# create  VIEW tpcds.part_view as  SELECT * FROM  tpcds.customer_details_view_v1 where  c_customer_sk =9527;
CREATE VIEW
newdb1=# select * from tpcds.part_view;
 c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
          9527 | 3             | James        | Cook
(1 row)
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3.创建物化视图

--创建基础数据
newdb1=# create table test(id serial primary key,testnum serial);
NOTICE:  CREATE TABLE will create implicit sequence "test_id_seq" for serial column "test.id"
NOTICE:  CREATE TABLE will create implicit sequence "test_testnum_seq" for serial column "test.testnum"
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "test_pkey" for table "test"
CREATE TABLE
newdb1=# insert into test(testnum) values(generate_series(1,100000));
INSERT 0 100000
--创建物化视图
newdb1=# create materialized view mv_test as
newdb1-# select * from test where testnum%2=0;
CREATE MATERIALIZED VIEW

--查看物化视图目前有多少行记录：
select count(*) from mv_test;
 count
-------
 50000
(1 row)

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4.手动更新物化视图

--变更数据
newdb1=# insert into test(testnum) values(generate_series(1,100000));
INSERT 0 100000
newdb1=# select count(*) from mv_test;
 count
-------
 50000
(1 row)
--手工更新
newdb1=#   refresh materialized view mv_test;
REFRESH MATERIALIZED VIEW
newdb1=#  select count(*) from mv_test;
 count
--------
 100000
(1 row)
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5.删除创建的视图

newdb1=# DROP MATERIALIZED VIEW mv_test;
DROP MATERIALIZED VIEW
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