TCS
Large multinational IT services and consulting enterprise based in India.
3 Rounds
~14 Days
Medium
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Technical Loop (3-4 Rounds)
Deep dive into domain knowledge, coding, and system design.
Interview Question Bank
Data Engineer
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Coding
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medium
What are Window functions in PySpark? Write a PySpark code snippet to calculate the running total of sales per region ordered by date.
#PySpark
#Window Functions
#Coding
Data Engineer
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Coding
•
medium
Write a PySpark snippet to flatten a deeply nested JSON structure containing arrays of structs.
#PySpark
#Data Manipulation
#JSON
Data Engineer
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Coding
•
medium
Write a PySpark script to read a CSV file, drop rows with null values in the 'customer_id' column, fill nulls in 'age' with the average age, and write to Parquet.
#PySpark
#Data Cleansing
#Coding
Data Engineer
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Technical
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hard
Your PySpark ETL job running on an AWS EMR cluster is failing with an 'Out Of Memory (OOM)' error. Walk me through your step-by-step debugging process.
#PySpark
#Troubleshooting
#Memory Management
Data Engineer
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Technical
•
medium
What is the difference between Cache() and Persist() in Spark? What are the different storage levels available?
#PySpark
#Caching
#Optimization
Data Engineer
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Technical
•
medium
In PySpark, what is the difference between a Broadcast Hash Join and a Sort Merge Join? When does Spark automatically choose a Broadcast Join?
#PySpark
#Joins
#Optimization
Data Engineer
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Technical
•
medium
Why are Python UDFs (User Defined Functions) considered bad for performance in PySpark, and what is the modern alternative?
#PySpark
#UDFs
#Optimization
Data Engineer
•
Technical
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hard
How do you achieve exactly-once processing semantics in an Apache Kafka to Spark Structured Streaming pipeline?
#Kafka
#Spark Streaming
#Architecture
Data Engineer
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Technical
•
medium
You notice a high consumer lag in your Kafka topic. What are the potential reasons, and how would you resolve it?
#Kafka
#Troubleshooting
#Streaming
Data Engineer
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Technical
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hard
You are joining a massive fact table with a dimension table in PySpark, and the job is stuck at 99% on the last task. How do you identify and resolve this issue?
#PySpark
#Data Skewness
#Performance Tuning
Data Engineer
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Technical
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easy
Explain the exact difference between repartition() and coalesce() in PySpark. If you are writing data to an Azure Data Lake, which one do you use to reduce the number of output files?
#PySpark
#Partitioning
#Shuffling
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