materializedView

1. in order to generate data for test, go to the application.properties and add app.generator.enabled=true after that app.generator.enabled=false
2. create tables and MATERIALIZED view
3. populated materialized view
4. create procedure for update view
5. time of update config in materializedViewRefresher.class

drop table if exists

drop table if EXISTS product CASCADE;
drop table if EXISTS users CASCADE;
drop table if EXISTS purchase_order CASCADE;

create data base:

CREATE TABLE users(
    id serial PRIMARY KEY,
    firstname VARCHAR (50),
    lastname VARCHAR (50),
    state VARCHAR(10)
 );
 
 CREATE TABLE product(
    id serial PRIMARY KEY,
    description VARCHAR (500),
    price numeric (10,2) NOT NULL
 );
 
 CREATE TABLE purchase_order(
     id serial PRIMARY KEY,
     user_id integer references users (id),
     product_id integer references product (id)
 );

create view :

create view purchase_order_summary
as
select u.state,
       sum(p.price) as total_sale
from users u,
     product p,
     purchase_order po
where u.id = po.user_id
  and p.id = po.product_id
group by u.state
order by u.state

create materializedView

CREATE MATERIALIZED VIEW purchase_order_summary
AS
select 
    u.state,
    sum(p.price) as total_sale
from 
    users u,
    product p,
    purchase_order po
where 
    u.id = po.user_id
    and p.id = po.product_id
group by u.state
order by u.state
WITH NO DATA;
CREATE UNIQUE INDEX state_category ON purchase_order_summary (state);

-- first population:
REFRESH MATERIALIZED VIEW purchase_order_summary;

create procedure:

-- create procedure
CREATE OR REPLACE PROCEDURE refresh_mat_view()
LANGUAGE plpgsql    
AS $$
BEGIN
  REFRESH MATERIALIZED VIEW CONCURRENTLY purchase_order_summary;
END;
$$;