From 347334dc26e23ad8121e35e62554986021306004 Mon Sep 17 00:00:00 2001
From: mnoskov <bather.plaint5x@icloud.com>
Date: Tue, 28 Apr 2026 04:30:01 +0300
Subject: [PATCH] =?UTF-8?q?=D0=A0=D0=90=D0=91=D0=9E=D0=A2=D0=90=20=D0=9D?=
 =?UTF-8?q?=D0=90=D0=94=20=D0=9E=D0=A8=D0=98=D0=91=D0=9A=D0=90=D0=9C=D0=98?=
 =?UTF-8?q?.=20=D0=9F=D0=B5=D1=82=20=D0=BF=D1=80=D0=BE=D0=B5=D0=BA=D1=82:?=
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 =?UTF-8?q?=D0=B3=D0=BE=D1=82=D0=BE=D0=B2=D0=BA=D0=B0=20=D0=B2=D0=B8=D1=82?=
 =?UTF-8?q?=D1=80=D0=B8=D0=BD=20=D0=B2=20Greenplum.?=
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---
 .../Пет проект: DWH/Step_3_core_layer.sql       |  2 ++
 .../Step_4_preparing_display_cases_at_greenplum.sql | 17 +++++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql b/mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql
index e03b401..a804a5c 100644
--- a/mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql	
+++ b/mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql	
@@ -157,6 +157,7 @@ SELECT
 FROM
 	generate_series('2023-01-01'::date, '2030-12-31'::date, INTERVAL '1 day') AS d;
 
+-- fact_lesson_views
 INSERT INTO core.fact_lesson_views (user_id, lesson_id, course_id, viewed_at)
 SELECT
 	raw_lv.user_id,
@@ -172,6 +173,7 @@ WHERE
 	AND raw_lv.user_id IS NOT NULL AND raw_lv.lesson_id IS NOT NULL
 	AND raw_l.course_id IS NOT NULL AND raw_lv.viewed_at IS NOT NULL;
 
+-- enrollments
 INSERT INTO core.enrollments (user_id, course_id, enrolled_at)
 SELECT
 	raw_e.user_id,
diff --git a/mnoskov/greenplum/Пет проект: DWH/Step_4_preparing_display_cases_at_greenplum.sql b/mnoskov/greenplum/Пет проект: DWH/Step_4_preparing_display_cases_at_greenplum.sql
index de2dac6..be37917 100644
--- a/mnoskov/greenplum/Пет проект: DWH/Step_4_preparing_display_cases_at_greenplum.sql	
+++ b/mnoskov/greenplum/Пет проект: DWH/Step_4_preparing_display_cases_at_greenplum.sql	
@@ -38,13 +38,22 @@ SELECT
 	du.name AS user_name,
 	du.email,
 	du.age,
-	0 AS enrollments_count,
+	e.enrollments_count,
 	du.registration_date
 FROM
 	core.dim_user du
+LEFT JOIN (
+	SELECT
+		user_id,
+		count(course_id) AS enrollments_count
+	FROM
+		core.enrollments
+	GROUP BY
+		user_id
+) e ON du.user_id = e.user_id
 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
+-- интересно, что при проверки плана запроса, когда кусок с enrollments_count был в CTE, выдавал какую-то хуйню, а когда я засунул его в подзапрос, сразу инлексы заработали, и строки начали эффективней читаться
 
 
 -- 9
@@ -60,7 +69,7 @@ WITH results_dim_course_lesson AS (
 	JOIN
 		core.dim_lesson dl ON dc.course_id = dl.course_id
 	GROUP BY
-		dc.course_id
+		dc.course_id, dc.title
 ),
 results_fact_lesson_views AS (
 	SELECT
@@ -79,7 +88,7 @@ SELECT
 	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
+	round(COALESCE(rflv.lessons_viewed, 0)::numeric / NULLIF(rdcl.lessons_in_course, 0), 2) AS completion_rate
 FROM
 	core.dim_user du
 JOIN