-- 0. Создаём БД
CREATE DATABASE dwh_db
    WITH OWNER = tester
         TEMPLATE = template0
         ENCODING = 'UTF8';

-- 1. Создём схемы
CREATE SCHEMA raw;      -- сырые данные
CREATE SCHEMA core;     -- или core. Тут хранилище: факты и измерения
CREATE SCHEMA dm;       -- BI-витрины


-- 2. Создаём raw-таблицы:

CREATE TABLE raw.users (
	id serial4 NOT NULL,
	"name" varchar(100) NOT NULL,
	age int4 NOT NULL,
	email varchar(100) NOT NULL,
	registration_date date NOT NULL,
	CONSTRAINT users_pkey PRIMARY KEY (id)
)
DISTRIBUTED BY (id);

CREATE TABLE raw.courses (
	id serial4 NOT NULL,
	title varchar(100) NOT NULL,
	category varchar(100) NOT NULL,
	created_at date NOT NULL,
	CONSTRAINT courses_pkey PRIMARY KEY (id)
)
DISTRIBUTED BY (id);

CREATE TABLE raw.lessons (
	id serial4 NOT NULL,
	course_id int4 NOT NULL,
	title varchar(100) NOT NULL,
	duration_min int4 NOT NULL,
	CONSTRAINT lessons_pkey PRIMARY KEY (id)
)
DISTRIBUTED BY (id);
ALTER TABLE raw.lessons ADD CONSTRAINT lessons_course_id_fkey FOREIGN KEY (course_id) REFERENCES raw.courses(id);

CREATE TABLE raw.enrollments (
	id serial4 NOT NULL,
	user_id int4 NOT NULL,
	course_id int4 NOT NULL,
	enrolled_at date NOT NULL,
	CONSTRAINT enrollments_pkey PRIMARY KEY (id)
)
DISTRIBUTED BY (id);
ALTER TABLE raw.enrollments ADD CONSTRAINT enrollments_course_id_fkey FOREIGN KEY (course_id) REFERENCES raw.courses(id);
ALTER TABLE raw.enrollments ADD CONSTRAINT enrollments_user_id_fkey FOREIGN KEY (user_id) REFERENCES raw.users(id);

CREATE TABLE raw.lesson_views (
	id serial4 NOT NULL,
	user_id int4 NOT NULL,
	lesson_id int4 NOT NULL,
	viewed_at timestamp NOT NULL,
	CONSTRAINT lesson_views_pkey PRIMARY KEY (id)
)
DISTRIBUTED BY (id);
ALTER TABLE raw.lesson_views ADD CONSTRAINT lesson_views_lesson_id_fkey FOREIGN KEY (lesson_id) REFERENCES raw.lessons(id);
ALTER TABLE raw.lesson_views ADD CONSTRAINT lesson_views_user_id_fkey FOREIGN KEY (user_id) REFERENCES raw.users(id);