user_activity_summary materialized view

mdrozdov/postgresql/dm_user_activity_summary.sql

@@ -0,0 +1,84 @@
+CREATE MATERIALIZED VIEW dm_user_activity_summary as 
+with enrollment_counts as(
+	select user_id, 
+		   count(course_id) as enrollment_count
+	from enrollments e
+	group by user_id
+),views as(
+	select user_id, 
+		count(distinct lesson_id) as viewed_lessons_count,
+		min(viewed_at) as first_view, 
+		max(viewed_at) as last_view
+	from lessons_views
+	group by user_id
+), total_lessons as(
+	select 	user_id, 
+			count(*) as total_lessons
+	from enrollments e
+	join lessons using(course_id)
+	group by user_id
+	order by user_id
+), engagment_rate as (
+	select tl.user_id, round(v.viewed_lessons_count*100.0/total_lessons, 2) as engagment_rate
+	from total_lessons tl
+	join views v using(user_id) 
+)
+select u.id, u.name, enrollment_count, viewed_lessons_count, last_view, first_view, engagment_rate
+from users u
+join enrollment_counts ec on u.id = ec.user_id
+join views v on u.id = v.user_id 
+join engagment_rate er on u.id = er.user_id
+order by u.id
+/*
+--первая попытка сделать витрину, делал избыточно с проверкой каждого подзапроса, поэтому забыл убрать order by, а также больше практиковался в оконных функциях
+CREATE MATERIALIZED VIEW user_activity_summary as
+with enrollment_counts as(
+	select distinct user_id, 
+		   count(course_id) over (partition by user_id) as enrollment_count
+	from enrollments e
+	order by user_id
+), viewed_lessons_count as (
+	select 
+			user_id, count(distinct lesson_id) as viewed_lessons_count
+	from lessons_views lv
+	group by user_id
+	order by user_id
+), first_views as(
+	select 
+			user_id,
+			viewed_at,
+			row_number() over (partition by user_id order by viewed_at asc) as rnf
+	from lessons_views
+), last_views as(
+	select 
+			user_id,
+			viewed_at,
+			row_number() over (partition by user_id order by viewed_at desc) as rnl
+	from lessons_views
+), result_views as(
+	select user_id, 
+		fw.viewed_at as first_view, 
+		lw.viewed_at as last_view
+	from first_views fw
+	join last_views lw using(user_id)
+	where rnf = 1 and rnl = 1
+), total_lessons as(
+	select 	user_id, 
+			count(*) as total_lessons
+	from enrollments e
+	join lessons using(course_id)
+	group by user_id
+	order by user_id
+), engagment_rate as (
+	select tl.user_id, round(vlc.viewed_lessons_count*100.0/total_lessons, 2) as engagment_rate
+	from total_lessons tl
+	join viewed_lessons_count vlc using(user_id) 
+)
+select u.id, u.name, enrollment_count, viewed_lessons_count, last_view, first_view, engagment_rate
+from users u
+join enrollment_counts ec on u.id = ec.user_id
+join viewed_lessons_count vlc on u.id = vlc.user_id
+join result_views rv on u.id = rv.user_id
+join engagment_rate er on u.id = er.user_id
+order by u.id
+*/