openGauss每日一练第18天|视图管理

1.创建表，创建普通视图。

--创建模式、表和插入数据
su - omm
sql -r
Create schema mytpcds;
CREATE TABLE mytpcds.mycustomer(c_mycustomer_sk integer,c_mycustomer_id char(5),c_first_name char(6),c_last_name char(8));
INSERT INTO mytpcds.mycustomer VALUES (6885, 1, 'Joes', 'Hunter'),(4321, 2, 'Lily','Carter'),(9527, 3, 'James', 'Cook'),(9500, 4, 'Lucy', 'Baker');
--创建视图
CREATE VIEW mytpcds.mycustomer_details_view_v1 AS SELECT * FROM mytpcds.mycustomer WHERE c_mycustomer_sk > 5400;
--查看视图内容
select * from mytpcds.mycustomer_details_view_v1;

root@modb:~# su - omm
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=# Create schema mytpcds;
CREATE SCHEMA
omm=# CREATE TABLE mytpcds.mycustomer(c_mycustomer_sk integer,c_mycustomer_id char(5),c_first_name char(6),c_last_name char(8));
CREATE TABLE
omm=# INSERT INTO mytpcds.mycustomer VALUES (6885, 1, 'Joes', 'Hunter'),(4321, 2, 'Lily','Carter'),(9527, 3, 'James', 'Cook'),(9500, 4, 'Lucy', 'Baker');
INSERT 0 4
omm=# CREATE VIEW mytpcds.mycustomer_details_view_v1 AS SELECT * FROM mytpcds.mycustomer WHERE c_mycustomer_sk > 5400;
CREATE VIEW
omm=# select * from mytpcds.mycustomer_details_view_v1;
 c_mycustomer_sk | c_mycustomer_id | c_first_name | c_last_name 
-----------------+-----------------+--------------+-------------
            6885 | 1               | Joes         | Hunter  
            9527 | 3               | James        | Cook    
            9500 | 4               | Lucy         | Baker   
(3 rows)

omm=# 

2.使用视图创建新的视图。

create  VIEW mytpcds.part_view as SELECT * FROM mytpcds.mycustomer_details_view_v1 where c_mycustomer_sk =9527;
--查看新的视图
select * from mytpcds.part_view;

omm=# create  VIEW mytpcds.part_view as SELECT * FROM mytpcds.mycustomer_details_view_v1 where c_mycustomer_sk =9527;
CREATE VIEW
omm=# select * from mytpcds.part_view;
 c_mycustomer_sk | c_mycustomer_id | c_first_name | c_last_name 
-----------------+-----------------+--------------+-------------
            9527 | 3               | James        | Cook    
(1 row)

omm=# 

3.创建物化视图。

--创建基表
drop materialized view if exists mv_mytest;
drop table if exists mytest;
create table mytest(id serial primary key,mytestnum serial);
insert into mytest(mytestnum) values(generate_series(1,100000));
--创建物化视图：
create materialized view mv_mytest as select * from mytest where mytestnum%2=0;
--查看物化视图目前有多少行记录：
select count(*) from mv_mytest;

omm=# drop materialized view if exists mv_mytest;
NOTICE:  materialized view "mv_mytest" does not exist, skipping
DROP MATERIALIZED VIEW
omm=# drop table if exists mytest;
NOTICE:  table "mytest" does not exist, skipping
DROP TABLE
omm=# create table mytest(id serial primary key,mytestnum serial);
NOTICE:  CREATE TABLE will create implicit sequence "mytest_id_seq" for serial column "mytest.id"
NOTICE:  CREATE TABLE will create implicit sequence "mytest_mytestnum_seq" for serial column "mytest.mytestnum"
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "mytest_pkey" for table "mytest"
CREATE TABLE
omm=# insert into mytest(mytestnum) values(generate_series(1,100000));
INSERT 0 100000
omm=# create materialized view mv_mytest as select * from mytest where mytestnum%2=0;
CREATE MATERIALIZED VIEW
omm=# select count(*) from mv_mytest;
 count 
-------
 50000
(1 row)

omm=# 

4.手动更新物化视图。

--向基表mytest插入数据，查看物化视图有多少行记录：
insert into mytest(mytestnum) values(generate_series(1,100000));
select count(*) from mv_mytest;
--手动更新物化视图，并查看更新物化视图后，物化视图有多少行记录：
refresh materialized view mv_mytest;
select count(*) from mv_mytest;

omm=# insert into mytest(mytestnum) values(generate_series(1,100000));
INSERT 0 100000
omm=# select count(*) from mv_mytest;
 count 
-------
 50000
(1 row)

omm=# refresh materialized view mv_mytest;
REFRESH MATERIALIZED VIEW
omm=# select count(*) from mv_mytest;

 count  
--------
 100000
(1 row)

omm=# 

5.删除创建的视图。

--删除普通视图
DROP view mytpcds.part_view;
DROP view mytpcds.mycustomer_details_view_v1;
--删除物化视图
DROP MATERIALIZED VIEW mv_mytest;

omm=# DROP view mytpcds.part_view;
DROP VIEW
omm=# DROP view mytpcds.mycustomer_details_view_v1;
omm=# DROP VIEW
omm=# DROP MATERIALIZED VIEW mv_mytest;
DROP MATERIALIZED VIEW