Month-Over-Month Engagement Growth | Dataford Interview Questions

Your question is Month-Over-Month Engagement Growth. Start with the requirements and the two tables on the right.

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Problem

Netflix Analytics Engineering needs a regional view of monthly content engagement across the Netflix catalog. Write a PostgreSQL query that calculates total watch minutes and month-over-month growth for each region.

Requirements

Join viewing events to netflix_titles so only events for known titles are included.
Aggregate positive watch minutes by region and calendar month for Q1 2025, excluding events with a missing region.
Use a window function to return the previous reported month’s engagement and calculate percentage growth. Return NULL growth when no prior month exists or the prior value is zero.
Sort the results by region and month in ascending order.

Schema

viewing_events

Column	Type	Description
event_idPK	INT	Unique viewing event identifier
title_id	INT	Referenced Netflix title identifier
region	VARCHAR(20)	Viewer region
viewed_at	TIMESTAMP	Timestamp when content was watched
watch_minutes	INT	Minutes watched during the event

netflix_titles

Column	Type	Description
title_idPK	INT	Unique Netflix title identifier
title_name	VARCHAR(150)	Netflix movie or series name
content_type	VARCHAR(20)	Content classification