openGauss每日一练第18天 | 视图

课程学习

1.创建视图

–创建模式、表和插入数据
su - omm
gsql -r

omm=# Create schema tpcds;
CREATE SCHEMA
omm=# CREATE TABLE tpcds.customer
omm-# (  c_customer_sk             integer,   
omm(#   c_customer_id             char(5),    
omm(#   c_first_name              char(6),    
omm(# omm(# ) ;
  c_last_name               char(8) 
CREATE TABLE
omm=# INSERT INTO tpcds.customer VALUES    
omm-# (6885, 1, 'Joes', 'Hunter'),    
omm-# (4321, 2, 'Lily','Carter'),    
omm-# (9527, 3, 'James', 'Cook'),
omm-# (9500, 4, 'Lucy', 'Baker');
INSERT 0 4

–创建视图

omm=# CREATE VIEW tpcds.customer_details_view_v1 AS
omm-# omm-# SELECT * FROM tpcds.customer
WHERE c_customer_sk > 5400;
CREATE VIEW

–查看视图内容

omm=# 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)

2.基于视图建立新的视图

omm=# create  VIEW tpcds.part_view as  SELECT * FROM  tpcds.customer_details_view_v1 where  c_customer_sk =9527;
CREATE VIEW

–查看新的视图

omm=# select * from tpcds.part_view;
 c_customer_sk | c_customer_id | c_first_name | c_last_name 
---------------+---------------+--------------+-------------
          9527 | 3             | James        | Cook    
(1 row)

3.创建物化视图

–创建基表

omm=# drop materialized view if exists mv_test;
NOTICE:  materialized view "mv_test" does not exist, skipping
DROP MATERIALIZED VIEW
omm=# drop table if exists test;
NOTICE:  table "test" does not exist, skipping
DROP TABLE
omm=# 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
omm=# insert into test(testnum) values(generate_series(1,100000));
INSERT 0 100000

–创建物化视图：

omm=# create materialized view mv_test as 
select * from test where testnum%2=0;
CREATE MATERIALIZED VIEW

–查看物化视图目前有多少行记录：

omm=# select count(*) from mv_test;
 count 
-------
 50000
(1 row)

4.普通视图相关的系统表pg_views

–系统视图pg_views

omm=# select * from pg_views where schemaname = 'tpcds' or schemaname = 'public';
 schemaname |         viewname         | viewowner |                                              definition                                              
------------+--------------------------+-----------+------------------------------------------------------------------------------------------------------
 tpcds      | customer_details_view_v1 | omm       | SELECT  * FROM tpcds.customer WHERE (customer.c_customer_sk > 5400);
 tpcds      | part_view                | omm       | SELECT  * FROM tpcds.customer_details_view_v1 WHERE (customer_details_view_v1.c_customer_sk = 9527);
(2 rows)

5.物化视图相关的系统表GS_MATVIEW

–GS_MATVIEW系统表提供了关于数据库中每一个物化视图的信息。

omm=# select * from GS_MATVIEW;
 matviewid | mapid | ivm | needrefresh | refreshtime 
-----------+-------+-----+-------------+-------------
     16412 |     0 | f   |             | 
(1 row)

6.手动更新物化视图

–向基表test插入数据，查看物化视图有多少行记录：

omm=# insert into test(testnum) values(generate_series(1,100000));
INSERT 0 100000
omm=# select count(*) from mv_test;
 count 
-------
 50000
(1 row)

–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：

omm=#   refresh materialized view mv_test;
REFRESH MATERIALIZED VIEW
omm=#  select count(*) from mv_test;
 count  
--------
 100000
(1 row)

7.删除视图

–删除普通视图

omm=# DROP view tpcds.part_view;
DROP VIEW
omm=# DROP view TPCDS.customer_details_view_v1;
DROP VIEW

–删除物化视图

omm=# DROP MATERIALIZED VIEW mv_test;
DROP MATERIALIZED VIEW

课程作业

1.创建表，创建普通视图

omm=# CREATE TABLE fund
omm-# (
omm(#     f_name VARCHAR(100) NOT NULL,
omm(#     f_id INT PRIMARY KEY,
omm(#     f_type CHAR(20),
omm(#     f_amount INT,
omm(#     risk_level CHAR(20) NOT NULL,
omm(#     f_manager INT NOT NULL
omm(# );
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "fund_pkey" for table "fund"
CREATE TABLE
omm=# 
omm=# 
omm=# INSERT INTO fund(f_name,f_id,f_type,f_amount,risk_level,f_manager) VALUES ('股票',1,'股票型',10000,'高',1);
INSERT 0 1
omm=# INSERT INTO fund(f_name,f_id,f_type,f_amount,risk_level,f_manager) VALUES ('投资',2,'债券型',10000,'中',2);
INSERT 0 1
omm=# INSERT INTO fund(f_name,f_id,f_type,f_amount,risk_level,f_manager) VALUES ('国债',3,'货币型',10000,'低',3);
INSERT 0 1
omm=# INSERT INTO fund(f_name,f_id,f_type,f_amount,risk_level,f_manager) VALUES ('沪深300指数',4,'指数型',10000,'中',4);
INSERT 0 1
omm=# create view v_fund as select f_name,f_id,f_type,risk_level from fund;
omm=# CREATE VIEW

omm=# select * from v_fund;
     f_name      | f_id |        f_type        |      risk_level      
-----------------+------+----------------------+----------------------
 股票          |    1 | 股票型            | 高                 
 投资          |    2 | 债券型            | 中                 
 国债          |    3 | 货币型            | 低                 
 沪深300指数 |    4 | 指数型            | 中                 
(4 rows)

2.使用视图创建新的视图

omm=# create  view vn_fund as select * from v_fund where f_id>2;
CREATE VIEW
omm=# select * from vn_fund;
     f_name      | f_id |        f_type        |      risk_level      
-----------------+------+----------------------+----------------------
 国债          |    3 | 货币型            | 低                 
 沪深300指数 |    4 | 指数型            | 中                 
(2 rows)

3.创建物化视图

omm=# create materialized view mv_fund as select * from fund;
omm=# CREATE MATERIALIZED VIEW
omm=# select * from mv_fund;
     f_name      | f_id |        f_type        | f_amount |      risk_level      | f_manager 
-----------------+------+----------------------+----------+----------------------+-----------
 股票          |    1 | 股票型            |    10000 | 高                  |         1
 投资          |    2 | 债券型            |    10000 | 中                  |         2
 国债          |    3 | 货币型            |    10000 | 低                  |         3
 沪深300指数 |    4 | 指数型            |    10000 | 中                  |         4
(4 rows)

4.手动更新物化视图

omm=# INSERT INTO fund(f_name,f_id,f_type,f_amount,risk_level,f_manager) VALUES ('股票1000',5,'股票型',10000,'高',5);
INSERT 0 1
omm=# 
omm=# select * from mv_fund;
     f_name      | f_id |        f_type        | f_amount |      risk_level      | f_manager 
-----------------+------+----------------------+----------+----------------------+-----------
 股票          |    1 | 股票型            |    10000 | 高                  |         1
 投资          |    2 | 债券型            |    10000 | 中                  |         2
 国债          |    3 | 货币型            |    10000 | 低                  |         3
 沪深300指数 |    4 | 指数型            |    10000 | 中                  |         4
(4 rows)
omm=# refresh materialized  view mv_fund;
REFRESH MATERIALIZED VIEW
omm=# select* from mv_fund;
     f_name      | f_id |        f_type        | f_amount |      risk_level      | f_manager 
-----------------+------+----------------------+----------+----------------------+-----------
 股票          |    1 | 股票型            |    10000 | 高                  |         1
omm=#  投资          |    2 | 债券型            |    10000 | 中                  |         2
 国债          |    3 | 货币型            |    10000 | 低                  |         3
 沪深300指数 |    4 | 指数型            |    10000 | 中                  |         4
 股票1000      |    5 | 股票型            |    10000 | 高                  |         5
(5 rows)

5.删除创建的视图

omm=# drop view vn_fund;
DROP VIEW
omm=# drop view v_fund;
DROP VIEW
omm=# drop materialized view mv_fund;
DROP MATERIALIZED VIEW
omm=# drop table fund;
DROP TABLE
omm=# \q