🔓 📢 Day 16/30 - DEEP DIVE SOLUTIONS: SQL, PYTHON, ETL, DATA MODELING
Solutions for March 17th, 2025 CHALLENGE – Unlock the Full Breakdown + Live Runnable Code! 🚀
👋 Hey Data Engineers!
Welcome to Day 16 of the 30-Day Data Engineering Challenge! 🚀
Today’s Deep Dive covers:🔓 📢 Day 16/30 - DEEP DIVE SOLUTIONS: SQL, PYTHON, ETL, DATA MODELIN
🚀 SQL: Recursive CTEs for Hierarchical Data
🔹 Learn how to retrieve all employees reporting to a manager, including indirect reports using recursive queries.
🐍 Python: Multi-threading & Performance
🔹 Understand when to use threading vs. multiprocessing for executing concurrent tasks efficiently.
⚡ ETL: Handling Failures in Data Pipelines
🔹 Discover best practices for retrying failed ETL jobs due to intermittent network issues.
📊 Data Modeling: Normalization vs. Denormalization
🔹 Learn when to denormalize a schema for analytical workloads vs. when to normalize for transactional integrity.
💡 What You’ll Learn:
✅ Concept breakdowns with clear explanations
✅ Live runnable code examples
✅ Best practices for real-world implementation
🔐 Upgrade to the Annual Plan to master these concepts like a pro!
📌 SQL Challenge - Recursive Queries for Hierarchical Data
Question: Which SQL query correctly retrieves all employees reporting to a given manager, including indirect reports?
✅ Answer: B) WITH RECURSIVE emp_cte AS (...) SELECT * FROM emp_cte;
Understanding Recursive CTEs
Recursive Common Table Expressions (CTEs) allow us to retrieve hierarchical data, such as:
✔ Organizational structures (employees & managers)
✔ File system directory structures
✔ Graph-based relationships
💻 Run & Test on onecompiler.com
1️⃣ Open onecompiler.com and select SQL (PostgreSQL).
2️⃣ Copy and paste the following SQL query:
