Написал витрину с общей отчётностью

gmokrousov/postgresql/DM_platform_summary.sql

@@ -0,0 +1,24 @@
+create materialized view platform_summary as 
+	with 
+        lv_stats as (
+            select 
+                count(distinct user_id) as users_with_views,
+                count(*)::decimal / count(distinct lesson_id) as avg_views_per_lesson
+            from lesson_views
+    	)
+	select 
+		total_users,
+		total_courses,
+		total_lessons,
+		users_with_views,
+		round((total_lessons::decimal / total_courses), 2) AS avg_lessons_per_course,
+		round(avg_views_per_lesson, 2) as avg_views_per_lesson
+	from 
+		(
+		select 
+			(select count(*) from users) as total_users,
+			(select count(*) from courses) as total_courses,
+			count(*) as total_lessons
+		from lessons
+	) as s
+	cross join lv_stats as lv;