Tech Mahindra

Tech Mahindra

Multinational IT services and consulting company.

4 Rounds ~21 Days Medium
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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 • Behavioral • medium

Tell me about a time you had to push back on a client or stakeholder who demanded an unrealistic deadline for a data delivery.

#Stakeholder Management #Communication
Practice
Data Engineer • Behavioral • medium

How do you handle a situation where the upstream source system changes its data format (e.g., adding/removing columns) without notifying the data engineering team?

#Problem Solving #Resilience
Practice
Data Engineer • Behavioral • hard

Describe the most challenging bug you have faced in a production data pipeline. How did you troubleshoot and resolve it?

#Troubleshooting #Experience
Practice
Data Engineer • Behavioral • easy

Working at an IT services company often means handling multiple client deliverables at once. How do you prioritize your tasks?

#Time Management #Prioritization
Practice
Data Engineer • Behavioral • medium

Explain the concept of 'Data Partitioning' to a non-technical business stakeholder.

#Communication #Mentoring
Practice
Data Engineer • Coding • medium

Write a SQL query to find the 3rd highest salary from an Employee table without using the LIMIT keyword.

#Subqueries #Correlated Queries #Window Functions
Practice
Data Engineer • Coding • medium

Given a table of Telecom Call Detail Records (CDRs), write a SQL query to calculate the rolling 7-day cumulative data usage for each specific user.

#Window Functions #Time Series #Data Aggregation
Practice
Data Engineer • Coding • medium

How do you find and delete duplicate records in a massive SQL table without creating a temporary table?

#Data Cleansing #CTEs #DELETE Statements
Practice
Data Engineer • Coding • medium

Write a Python script using Pandas or PySpark to read a 10GB CSV file, drop rows where the 'customer_id' is null, and write the output partitioned by 'region' into Parquet format.

#Data I/O #Data Cleaning #Partitioning
Practice
Data Engineer • Coding • easy

Write a Python function to find the first non-repeating character in a given string. Optimize it for time complexity.

#Strings #Hash Maps
Practice
Data Engineer • Coding • medium

You need to extract data from a third-party REST API for a client project. The API limits responses to 100 records per request. Write a Python snippet to handle pagination and extract all records.

#API Integration #Pagination #Requests Library
Practice
Data Engineer • Coding • easy

Given a list of dictionaries representing employee data (id, name, department), write Python code to group the employees by department.

#Data Manipulation #Dictionaries #Collections
Practice
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
Practice
Data Engineer • Coding • medium

Write a SQL query to pivot a table containing 'Year', 'Month', and 'Revenue' so that each Month becomes a column with the corresponding Revenue.

#Pivot #Data Transformation
Practice
Data Engineer • Coding • easy

Write a Python script to connect to an AWS S3 bucket, list all files with a '.json' extension, and print their sizes.

#Boto3 #AWS #Scripting
Practice
Data Engineer • System Design • medium

Design an ETL pipeline on AWS to ingest daily Call Detail Records (CDRs) from an SFTP server, transform them, and load them into Redshift for reporting.

#AWS #ETL Architecture #Data Warehousing
Practice
Data Engineer • System Design • hard

Design a real-time streaming pipeline to process IoT sensor data from manufacturing plants, detect anomalies, and store the results.

#Streaming #Kafka #Spark Streaming #NoSQL
Practice
Data Engineer • System Design • hard

A healthcare client wants to move from a traditional data warehouse to a Data Lakehouse architecture. How would you design this using Databricks?

#Data Lakehouse #Databricks #Medallion Architecture
Practice
Data Engineer • System Design • hard

Design a batch processing pipeline to ingest 500GB of transactional data daily. How do you handle incremental loads?

#Batch Processing #Incremental Load #Architecture
Practice
Data Engineer • Technical • medium

How do you schedule and monitor your data pipelines? Explain the core components of Apache Airflow.

#Airflow #Orchestration
Practice
Data Engineer • Technical • easy

Explain the difference between ROW_NUMBER(), RANK(), and DENSE_RANK(). Provide a scenario where you would specifically choose DENSE_RANK() over RANK().

#Window Functions #Data Ranking
Practice
Data Engineer • Technical • hard

A client complains that a critical reporting query taking data from a 50-million row table is running too slow. Walk me through your step-by-step approach to optimize it.

#Query Optimization #Indexing #Execution Plans
Practice
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
Practice
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
Practice
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
Practice
Data Engineer • Technical • easy

Explain the concept of Lazy Evaluation in Spark. Why is it beneficial for performance?

#Spark Core #Transformations vs Actions
Practice
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
Practice
Data Engineer • Technical • medium

In Azure Data Factory (ADF), how do you design a dynamic pipeline that can copy data from 50 different on-premise SQL Server tables to Azure Data Lake without creating 50 separate copy activities?

#Azure Data Factory #Dynamic Pipelines #Metadata Driven ETL
Practice
Data Engineer • Technical • medium

Explain the architecture of Snowflake. How does its separation of storage and compute benefit a multi-tenant client environment?

#Snowflake #Cloud Architecture
Practice
Data Engineer • Technical • medium

What is Slowly Changing Dimension (SCD) Type 2? Explain how you would implement it in a data warehouse.

#Dimensional Modeling #SCD
Practice
Data Engineer • Technical • easy

Compare Star Schema and Snowflake Schema. If a client prioritizes query read performance over storage space, which would you recommend and why?

#Data Modeling #Schema Design
Practice
Data Engineer • Technical • medium

How do you ensure data quality and integrity in your ETL pipelines? What specific checks do you automate?

#Data Validation #Testing
Practice
Data Engineer • Technical • easy

Explain your Git workflow for deploying data engineering code across Development, QA, and Production environments.

#CI/CD #Version Control
Practice
Data Engineer • Technical • medium

What is 'Idempotency' in the context of data engineering? Why is it critical for data pipelines?

#Pipeline Design #Reliability
Practice
Data Engineer • Technical • easy

In PySpark, what is the difference between repartition() and coalesce()? When should you use which?

#PySpark #Partitioning
Practice

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Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

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