pet-project

gp_pet_project.sql

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+-- ===============================================================
+-- SCHEMAS
+-- ===============================================================
+
+CREATE SCHEMA raw;
+CREATE SCHEMA core;
+CREATE SCHEMA dm;
+
+
+-- ===============================================================
+-- DIMENSIONS
+-- ===============================================================
+
+-- dim_user
+CREATE TABLE core.dim_user (
+    user_id INT PRIMARY KEY,
+    name TEXT,
+    age INT,
+    email TEXT,
+    registration_date DATE
+)
+DISTRIBUTED REPLICATED;
+
+INSERT INTO core.dim_user (user_id, name, age, email, registration_date)
+SELECT DISTINCT
+    user_id::INT,
+    name::TEXT,
+    age::INT,
+    email::TEXT,
+    registration_date::DATE
+FROM raw.users;
+
+
+-- dim_course
+CREATE TABLE core.dim_course (
+    course_id INT PRIMARY KEY,
+    title TEXT,
+    category TEXT
+)
+DISTRIBUTED REPLICATED;
+
+INSERT INTO core.dim_course (course_id, title, category)
+SELECT DISTINCT
+    id::INT,
+    title::TEXT,
+    category::TEXT
+FROM raw.courses;
+
+
+-- dim_lesson
+CREATE TABLE core.dim_lesson (
+    lesson_id INT PRIMARY KEY,
+    title TEXT,
+    duration_min INT,
+    course_id INT REFERENCES core.dim_course(course_id)
+)
+DISTRIBUTED REPLICATED;
+
+INSERT INTO core.dim_lesson (lesson_id, title, duration_min, course_id)
+SELECT DISTINCT
+    id::INT,
+    title::TEXT,
+    duration_min::INT,
+    course_id::INT
+FROM raw.lessons;
+
+
+-- dim_date (optional)
+CREATE TABLE core.dim_date (
+    date DATE PRIMARY KEY,
+    year INT,
+    month INT,
+    day INT,
+    weekday TEXT
+)
+DISTRIBUTED REPLICATED;
+
+
+-- ===============================================================
+-- FACT TABLES
+-- ===============================================================
+
+-- fact_lesson_views
+CREATE TABLE core.fact_lesson_views (
+    user_id INT REFERENCES core.dim_user(user_id),
+    lesson_id INT REFERENCES core.dim_lesson(lesson_id),
+    course_id INT REFERENCES core.dim_course(course_id),
+    viewed_at TIMESTAMP
+)
+DISTRIBUTED REPLICATED;
+
+INSERT INTO core.fact_lesson_views (user_id, lesson_id, course_id, viewed_at)
+SELECT DISTINCT
+    lv.user_id::INT,
+    lv.lesson_id::INT,
+    l.course_id::INT,
+    lv.viewed_at::TIMESTAMP
+FROM raw.lesson_views lv
+JOIN raw.lessons l ON l.id = lv.lesson_id;
+
+
+-- enrollments
+CREATE TABLE core.enrollments (
+    user_id INT REFERENCES core.dim_user(user_id),
+    course_id INT REFERENCES core.dim_course(course_id),
+    enrolled_at TIMESTAMP
+)
+DISTRIBUTED REPLICATED;
+
+INSERT INTO core.enrollments (user_id, course_id, enrolled_at)
+SELECT DISTINCT
+    user_id::INT,
+    course_id::INT,
+    enrolled_at::TIMESTAMP
+FROM raw.enrollments;
+
+
+-- ===============================================================
+-- VITRINA 7 — Lesson Popularity
+-- ===============================================================
+
+/* ===============================================================
+  ЗАДАНИЕ 7: Витрина dm.lesson_popularity_summary
+
+  Цель:
+    Показать популярность каждого урока.
+
+  Поля витрины:
+    - lesson_id      — идентификатор урока
+    - lesson_title   — название урока
+    - course_id      — идентификатор курса
+    - course_title   — название курса
+    - total_views    — общее число просмотров урока
+    - unique_users   — количество уникальных пользователей
+    - first_view     — дата первого просмотра
+    - last_view      — дата последнего просмотра
+
+  Условия выполнения:
+    - JOIN fact_lesson_views, dim_lesson, dim_course
+    - Группировка по lesson_id, lesson_title, course_id, course_title
+    - Уникальные пользователи: COUNT(DISTINCT user_id)
+=============================================================== */
+
+CREATE MATERIALIZED VIEW dm.lesson_popularity_summary AS
+SELECT 
+    flv.lesson_id,
+    dl.title AS lesson_title,
+    flv.course_id,
+    dc.title AS course_title,
+    COUNT(*) AS total_views,
+    COUNT(DISTINCT flv.user_id) AS unique_users,
+    MIN(flv.viewed_at) AS first_view,
+    MAX(flv.viewed_at) AS last_view
+FROM core.fact_lesson_views flv
+LEFT JOIN core.dim_lesson dl ON dl.lesson_id = flv.lesson_id
+LEFT JOIN core.dim_course dc ON dc.course_id = flv.course_id
+GROUP BY flv.lesson_id, dl.title, flv.course_id, dc.title
+DISTRIBUTED REPLICATED;
+
+
+-- ===============================================================
+-- VITRINA — Inactive Users
+-- ===============================================================
+
+/* ===============================================================
+  ЗАДАНИЕ: Найти пользователей, которые не просмотрели ни одного урока.
+
+  Цель:
+    Определить невовлечённых пользователей и потенциальный отток.
+
+  Поля витрины:
+    - user_id            — идентификатор пользователя
+    - user_name          — имя
+    - email              — почта
+    - age                — возраст
+    - enrollments_count  — количество курсов
+    - registration_date  — дата регистрации
+
+  Условия выполнения:
+    - Пользователи, отсутствующие в fact_lesson_views
+    - LEFT JOIN dim_user + enrollments
+    - Фильтрация через NOT EXISTS
+=============================================================== */
+
+CREATE INDEX idx_fact_lesson_views_user 
+    ON core.fact_lesson_views (user_id);
+
+CREATE INDEX idx_enrollments_user_course 
+    ON core.enrollments (user_id, course_id);
+
+CREATE MATERIALIZED VIEW dm.inactive_users_summary AS
+SELECT 
+    du.user_id,
+    du.name AS user_name,
+    du.email,
+    du.age,
+    COUNT(e.course_id) AS enrollments_count,
+    du.registration_date
+FROM core.dim_user du
+LEFT JOIN core.enrollments e ON e.user_id = du.user_id
+WHERE NOT EXISTS (
+    SELECT 1
+    FROM core.fact_lesson_views fv
+    WHERE fv.user_id = du.user_id
+)
+GROUP BY du.user_id
+DISTRIBUTED REPLICATED;
+
+
+-- ===============================================================
+-- VITRINA 9 — Course Completion
+-- ===============================================================
+
+/* ===============================================================
+  ЗАДАНИЕ 9: Витрина dm.course_completion_rate
+
+  Цель:
+    Анализировать, насколько пользователи проходят курсы до конца.
+
+  Поля витрины:
+    - user_id            — идентификатор пользователя
+    - user_name          — имя пользователя
+    - course_id          — идентификатор курса
+    - course_title       — название курса
+    - total_lessons      — количество уроков в курсе
+    - lessons_viewed     — число просмотренных уроков
+    - completion_rate    — lessons_viewed / total_lessons
+
+  Условия выполнения:
+    - JOIN между dim_user, enrollments, dim_lesson, fact_lesson_views
+    - Вынести подсчёт уроков в отдельный CTE
+    - Учитывать просмотры по user_id + course_id
+    - Использовать NULLIF и ROUND
+=============================================================== */
+
+CREATE INDEX idx_user_course_lesson 
+    ON core.fact_lesson_views (user_id, course_id, lesson_id);
+
+CREATE INDEX idx_course_lesson 
+    ON core.dim_lesson (course_id, lesson_id);
+
+CREATE MATERIALIZED VIEW dm.course_completion_rate AS
+WITH viewed_stats AS (
+    SELECT 
+        user_id,
+        course_id,
+        COUNT(DISTINCT lesson_id) AS lessons_viewed
+    FROM core.fact_lesson_views
+    GROUP BY user_id, course_id
+),
+course_lessons AS (
+    SELECT 
+        course_id,
+        COUNT(DISTINCT lesson_id) AS total_lessons
+    FROM core.dim_lesson
+    GROUP BY course_id
+)
+SELECT
+    du.user_id,
+    du.name AS user_name,
+    c.course_id,
+    c.title AS course_title,
+    cl.total_lessons,
+    COALESCE(vs.lessons_viewed, 0) AS lessons_viewed,
+    ROUND(
+        COALESCE(vs.lessons_viewed, 0)::numeric 
+        / NULLIF(cl.total_lessons, 0),
+        2
+    ) AS completion_rate
+FROM core.enrollments e
+JOIN core.dim_user du ON du.user_id = e.user_id
+JOIN core.dim_course c ON c.course_id = e.course_id
+JOIN course_lessons cl ON cl.course_id = c.course_id
+LEFT JOIN viewed_stats vs 
+       ON vs.user_id = e.user_id 
+      AND vs.course_id = e.course_id
+DISTRIBUTED REPLICATED;
+
+
+-- ===============================================================
+-- TEST SELECTS
+-- ===============================================================
+
+SELECT * FROM dm.lesson_popularity_summary LIMIT 10;
+SELECT * FROM dm.inactive_users_summary LIMIT 10;
+SELECT * FROM dm.course_completion_rate LIMIT 10;