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Netflix Analytics Engineer Interview Question (SQL) 🚀
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### Scenario Overview
Netflix wants to analyze user engagement with their platform. Imagine you have a table called netflix_data with the following columns:
- user_id: Unique identifier for each user
- subscription_plan: Type of subscription (e.g., Basic, Standard, Premium)
- genre: Genre of the content the user watched (e.g., Drama, Comedy, Action)
- timestamp: Date and time when the user watched a show
- watch_duration: Length of time (in minutes) a user spent watching
- country: User’s country

The main objective is to figure out how to get insights into user behavior, such as which genres are most popular or how watch duration varies across subscription plans.

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### Typical Interview Question

> “Using the netflix_data table, find the top 3 genres by average watch duration in each subscription plan, and return both the genre and the average watch duration.”

This question tests your ability to:
1. Filter or group data by subscription plan.
2. Calculate average watch duration within each group.
3. Sort results to find the “top 3” within each group.
4. Handle tie situations or edge cases (e.g., if there are fewer than 3 genres).

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### Step-by-Step Approach

1. Group and Aggregate
Use the GROUP BY clause to group by subscription_plan and genre. Then, use an aggregate function like AVG(watch_duration) to get the average watch time for each combination.

2. Rank Genres
You can utilize a window function—commonly ROW_NUMBER() or RANK()—to assign a ranking to each genre within its subscription plan, based on the average watch duration. For example:

   AVG(watch_duration) OVER (PARTITION BY subscription_plan ORDER BY AVG(watch_duration) DESC)
   

(Note that in many SQL dialects, you’ll need a subquery because you can’t directly apply an aggregate in the ORDER BY of a window function.)

3. Select Top 3
After ranking rows in each partition (i.e., subscription plan), pick only the top 3 by watch duration. This could look like:

   SELECT subscription_plan,
          genre,
          avg_watch_duration
   FROM (
       SELECT subscription_plan,
              genre,
              AVG(watch_duration) AS avg_watch_duration,
              ROW_NUMBER() OVER (
                  PARTITION BY subscription_plan 
                  ORDER BY AVG(watch_duration) DESC
              ) AS rn
       FROM netflix_data
       GROUP BY subscription_plan, genre
   ) ranked
   WHERE rn <= 3;
   

4. Validate Results
- Make sure each subscription plan returns up to 3 genres.
- Check for potential ties. Depending on the question, you might use RANK() or DENSE_RANK() to handle ties differently.
- Confirm the data type and units for watch_duration (minutes, seconds, etc.).

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### Key Takeaways
- Window Functions: Essential for ranking or partitioning data.
- Aggregations & Grouping: A foundational concept for Analytics Engineers.
- Data Validation: Always confirm you’re interpreting columns (like watch_duration) correctly.

By mastering these techniques, you’ll be better prepared for SQL interview questions that delve into real-world scenarios—especially at a data-driven company like Netflix.

📖 Data Engineering Roadmap 2025

𝟭. 𝗖𝗹𝗼𝘂𝗱 𝗦𝗤𝗟 (𝗔𝗪𝗦 𝗥𝗗𝗦, 𝗚𝗼𝗼𝗴𝗹𝗲 𝗖𝗹𝗼𝘂𝗱 𝗦𝗤𝗟, 𝗔𝘇𝘂𝗿𝗲 𝗦𝗤𝗟)

💡 Why? Cloud-managed databases are the backbone of modern data platforms.

✅ Serverless, scalable, and cost-efficient
✅ Automated backups & high availability
✅ Works seamlessly with cloud data pipelines

𝟮. 𝗱𝗯𝘁 (𝗗𝗮𝘁𝗮 𝗕𝘂𝗶𝗹𝗱 𝗧𝗼𝗼𝗹) – 𝗧𝗵𝗲 𝗙𝘂𝘁𝘂𝗿𝗲 𝗼𝗳 𝗘𝗟𝗧

💡 Why? Transform data inside your warehouse (Snowflake, BigQuery, Redshift).

✅ SQL-based transformation – easy to learn
✅ Version control & modular data modeling
✅ Automates testing & documentation

𝟯. 𝗔𝗽𝗮𝗰𝗵𝗲 𝗔𝗶𝗿𝗳𝗹𝗼𝘄 – 𝗪𝗼𝗿𝗸𝗳𝗹𝗼𝘄 𝗢𝗿𝗰𝗵𝗲𝘀𝘁𝗿𝗮𝘁𝗶𝗼𝗻

💡 Why? Automate and schedule complex ETL/ELT workflows.

✅ DAG-based orchestration for dependency management
✅ Integrates with cloud services (AWS, GCP, Azure)
✅ Highly scalable & supports parallel execution

𝟰. 𝗗𝗲𝗹𝘁𝗮 𝗟𝗮𝗸𝗲 – 𝗧𝗵𝗲 𝗣𝗼𝘄𝗲𝗿 𝗼𝗳 𝗔𝗖𝗜𝗗 𝗶𝗻 𝗗𝗮𝘁𝗮 𝗟𝗮𝗸𝗲𝘀

💡 Why? Solves data consistency & reliability issues in Apache Spark & Databricks.
✅ Supports ACID transactions in data lakes
✅ Schema evolution & time travel
✅ Enables incremental data processing

𝟱. 𝗖𝗹𝗼𝘂𝗱 𝗗𝗮𝘁𝗮 𝗪𝗮𝗿𝗲𝗵𝗼𝘂𝘀𝗲𝘀 (𝗦𝗻𝗼𝘄𝗳𝗹𝗮𝗸𝗲, 𝗕𝗶𝗴𝗤𝘂𝗲𝗿𝘆, 𝗥𝗲𝗱𝘀𝗵𝗶𝗳𝘁)

💡 Why? Centralized, scalable, and powerful for analytics.
✅ Handles petabytes of data efficiently
✅ Pay-per-use pricing & serverless architecture

𝟲. 𝗔𝗽𝗮𝗰𝗵𝗲 𝗞𝗮𝗳𝗸𝗮 – 𝗥𝗲𝗮𝗹-𝗧𝗶𝗺𝗲 𝗦𝘁𝗿𝗲𝗮𝗺𝗶𝗻𝗴

💡 Why? For real-time event-driven architectures.
✅ High-throughput

𝟳. 𝗣𝘆𝘁𝗵𝗼𝗻 & 𝗦𝗤𝗟 – 𝗧𝗵𝗲 𝗖𝗼𝗿𝗲 𝗼𝗳 𝗗𝗮𝘁𝗮 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿𝗶𝗻𝗴

💡 Why? Every data engineer must master these!

✅ SQL for querying, transformations & performance tuning
✅ Python for automation, data processing, and API integrations

𝟴. 𝗗𝗮𝘁𝗮𝗯𝗿𝗶𝗰𝗸𝘀 – 𝗨𝗻𝗶𝗳𝗶𝗲𝗱 𝗔𝗻𝗮𝗹𝘆𝘁𝗶𝗰𝘀 & 𝗔𝗜

💡 Why? The go-to platform for big data processing & machine learning on the cloud.

✅ Built on Apache Spark for fast distributed computing

Different Types of Data Analyst Interview Questions
👇👇

Technical Skills: These questions assess your proficiency with data analysis tools, programming languages (e.g., SQL, Python, R), and statistical methods.

Case Studies: You might be presented with real-world scenarios and asked how you would approach and solve them using data analysis.

Behavioral Questions: These questions aim to understand your problem-solving abilities, teamwork, communication skills, and how you handle challenges.

Statistical Questions: Expect questions related to descriptive and inferential statistics, hypothesis testing, regression analysis, and other quantitative techniques.

Domain Knowledge: Some interviews might delve into your understanding of the specific industry or domain the company operates in.

Machine Learning Concepts: Depending on the role, you might be asked about your understanding of machine learning algorithms and their applications.

Coding Challenges: These can assess your programming skills and your ability to translate algorithms into code.

Communication: You might need to explain technical concepts to non-technical stakeholders or present your findings effectively.

Problem-Solving: Expect questions that test your ability to approach complex problems logically and analytically.

Remember, the exact questions can vary widely based on the company and the role you're applying for. It's a good idea to review the job description and the company's background to tailor your preparation.