Tech Mahindra
Multinational IT services and consulting company.
4 Rounds
~21 Days
Medium
The Interview Loop
Recruiter Screen (30 min)
Standard fit check, behavioral questions, and resume overview.
Technical Loop (3-4 Rounds)
Deep dive into domain knowledge, coding, and system design.
Interview Question Bank
Data Engineer
•
Coding
•
hard
Write a PySpark snippet to merge new incoming data into an existing Delta Lake table, updating existing records and inserting new ones (Upsert).
#Delta Lake
#PySpark
#Upserts
Data Engineer
•
Technical
•
medium
Explain the internal architecture of Apache Spark. What happens under the hood when you submit a Spark job?
#Spark Architecture
#Driver
#Executors
#Cluster Manager
Data Engineer
•
Technical
•
hard
During a data migration project, your PySpark job is running extremely slow and some tasks are taking much longer than others. How do you identify and resolve data skewness?
#Performance Tuning
#Data Skew
#Salting
Data Engineer
•
Technical
•
medium
What is the difference between a Broadcast Hash Join and a Sort Merge Join in Spark? When would you force a Broadcast join?
#Spark Joins
#Optimization
Data Engineer
•
Technical
•
easy
Explain the concept of Lazy Evaluation in Spark. Why is it beneficial for performance?
#Spark Core
#Transformations vs Actions
Data Engineer
•
Technical
•
hard
Your Spark job fails with an OutOfMemory (OOM) error on the executor side. What parameters would you tweak or what code changes would you make?
#Troubleshooting
#Memory Management
#Spark Configuration
Data Engineer
•
Technical
•
easy
In PySpark, what is the difference between repartition() and coalesce()? When should you use which?
#PySpark
#Partitioning
Difficulty Radar
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Senior EngineerFocuses on core competencies, system constraints, and clear communication.
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