CQRS-Pattern

1. run query with springQuery
2. run command with springCommand
3. for initialization:

##. for create table:

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 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 $$
BEGIN
  REFRESH MATERIALIZED VIEW CONCURRENTLY purchase_order_summary;
END;
$$;