Пет проект: DWH. Этап 4: Подготовка витрин в Greenplum.

mnoskov/greenplum/Пет проект: DWH/Step_4_preparing_display_cases_at_greenplum.sql

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+-- 7
+--DROP MATERIALIZED VIEW dm.lesson_popularity_summary;
+CREATE MATERIALIZED VIEW dm.lesson_popularity_summary AS
+WITH results_fact_lesson_views AS (
+	SELECT
+		flv.lesson_id,
+		count(flv.user_id) AS total_views,
+		count(DISTINCT flv.user_id) AS unique_users,
+		min(flv.viewed_at)::date AS first_view,
+		max(flv.viewed_at)::date AS last_view
+	FROM
+		core.fact_lesson_views flv
+	GROUP BY
+		flv.lesson_id
+)
+SELECT
+	dl.lesson_id,
+	dl.title AS lesson_title,
+	dl.course_id,
+	dc.title AS course_title,
+	rflv.total_views,
+	rflv.unique_users,
+	rflv.first_view,
+	rflv.last_view
+FROM
+	core.dim_lesson dl
+JOIN
+	core.dim_course dc ON dl.course_id = dc.course_id
+LEFT JOIN
+	results_fact_lesson_views rflv ON dl.lesson_id = rflv.lesson_id;
+
+
+-- 8
+--DROP MATERIALIZED VIEW dm.inactive_users_summary;
+CREATE MATERIALIZED VIEW dm.inactive_users_summary AS
+SELECT
+	du.user_id,
+	du.name AS user_name,
+	du.email,
+	du.age,
+	0 AS enrollments_count,
+	du.registration_date
+FROM
+	core.dim_user du
+WHERE
+	NOT EXISTS (SELECT 1 FROM core.fact_lesson_views flv WHERE flv.user_id = du.user_id);
+-- тут странно, в условии сказано зачем-то enrollment присоединять, но делается все и без него отлично
+
+
+-- 9
+--DROP MATERIALIZED VIEW dm.course_completion_rate;
+CREATE MATERIALIZED VIEW dm.course_completion_rate AS
+WITH results_dim_course_lesson AS (
+	SELECT
+		dc.course_id,
+		dc.title,
+		count(lesson_id) AS lessons_in_course
+	FROM
+		core.dim_course dc
+	JOIN
+		core.dim_lesson dl ON dc.course_id = dl.course_id
+	GROUP BY
+		dc.course_id
+),
+results_fact_lesson_views AS (
+	SELECT
+		flv.user_id,
+		flv.course_id,
+		count(DISTINCT lesson_id) AS lessons_viewed
+	FROM
+		core.fact_lesson_views flv
+	GROUP BY
+		flv.user_id, flv.course_id
+)
+SELECT
+	du.user_id,
+	du.name AS user_name,
+	rdcl.course_id,
+	rdcl.title AS course_title,
+	rdcl.lessons_in_course,
+	COALESCE(rflv.lessons_viewed, 0) AS lessons_viewed,
+	round(COALESCE(rflv.lessons_viewed, 0) / NULLIF(rdcl.lessons_in_course, 0)::numeric, 2) AS completion_rate
+FROM
+	core.dim_user du
+JOIN
+	core.enrollments e ON du.user_id = e.user_id
+JOIN
+	results_dim_course_lesson rdcl ON e.course_id = rdcl.course_id
+LEFT JOIN
+	results_fact_lesson_views rflv ON e.user_id = rflv.user_id AND e.course_id = rflv.course_id;