Deloitte

Multinational professional services network with offices in over 150 countries.

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

All Roles Backend Engineer 35 Cloud Engineer 35 Data Engineer 35 Data Scientist 35 DevOps Engineer 35 Frontend Engineer 35 Full Stack Engineer 35 Machine Learning Engineer 35 Product Manager 35 Software Engineer 35

All Topics SQL 6 Big Data 5 Culture Fit 4 System Design 3 Data Modeling 2 Cloud 2 Data Warehousing 2 Python 2

Data Engineer • Behavioral • medium

Tell me about a time when a client drastically changed the requirements of a data pipeline midway through the sprint. How did you handle it?

#Client Management #Agile #Adaptability

Practice

Data Engineer • Behavioral • easy

As a consultant, you often work with non-technical business stakeholders. Give an example of how you explained a complex data architecture concept to a non-technical client.

#Consulting #Stakeholder Management #Communication

Practice

Data Engineer • Behavioral • medium

Describe a situation where you faced scope creep on a data engineering project. How did you manage it while keeping the client satisfied?

#Project Management #Consulting #Negotiation

Practice

Data Engineer • Behavioral • medium

Tell me about a time you had to deliver a critical data project under a very tight deadline. How did you prioritize your tasks?

#Time Management #Prioritization #Stress Management

Practice

Data Engineer • Behavioral • medium

Describe a time when you disagreed with a Senior Architect or Manager regarding a technical design. How did you handle the situation?

#Conflict Resolution #Communication #Teamwork

Practice

Data Engineer • Behavioral • medium

Tell me about a time you identified an inefficiency in a process or architecture and optimized it, resulting in cost savings for the client or your company.

#Cost Optimization #Initiative #Value Delivery

Practice

Data Engineer • Behavioral • easy

Consultants often have to learn new tools on the fly. Tell me about a time you had to quickly adapt to a new technology stack for a project. How did you get up to speed?

#Continuous Learning #Adaptability

Practice

Data Engineer • Coding • medium

Write a SQL query to find the top 3 highest-paid employees in each department. If there is a tie, they should have the same rank.

#Window Functions #DENSE_RANK #Joins

Practice

Data Engineer • Coding • medium

Write a Python script to parse a deeply nested JSON file containing client transaction data, flatten it, and convert it into a Pandas DataFrame.

#Data Manipulation #JSON #Pandas

Practice

Data Engineer • Coding • medium

Write a SQL query to calculate the cumulative sum of revenue per month for the year 2023.

#Window Functions #Aggregations

Practice

Data Engineer • Coding • medium

You have a table with millions of rows and no primary key. Write a SQL query to delete all duplicate rows, keeping only one instance of each.

#Data Cleansing #CTEs #ROW_NUMBER

Practice

Data Engineer • Coding • hard

Write a recursive CTE in SQL to output a company's organizational chart, showing each employee's name, their manager's name, and their depth level in the hierarchy.

#Recursive CTE #Hierarchical Data

Practice

Data Engineer • Coding • easy

Write a Python function to merge two sorted lists of integers into a single sorted list without using the built-in sort() or sorted() functions.

#Two Pointers #Arrays

Practice

Data Engineer • System Design • medium

Design a Slowly Changing Dimension (SCD) Type 2 process for a client's customer dimension table. How would you implement this in a cloud data warehouse like Snowflake or Redshift?

#SCD Type 2 #Data Modeling #ETL

Practice

Data Engineer • System Design • medium

A healthcare client wants to build a Data Lakehouse on Azure/Databricks. Design a Medallion Architecture (Bronze, Silver, Gold) for their patient records and claims data.

#Data Lakehouse #Medallion Architecture #Databricks

Practice

Data Engineer • System Design • hard

A large retail client wants to migrate their on-premise Hadoop cluster to AWS. Walk me through your migration strategy, including tool selection and risk mitigation.

#Cloud Migration #AWS #Hadoop

Practice

Data Engineer • System Design • hard

Design a real-time streaming pipeline to detect fraudulent credit card transactions. The system must process 10,000 events per second with sub-second latency.

#Streaming #Kafka #Spark Streaming #Fraud Detection

Practice

Data Engineer • System Design • hard

How do you handle 'late-arriving facts' in a data warehouse where the fact record arrives before its corresponding dimension record?

#ETL #Dimensional Modeling #Data Integrity

Practice

Data Engineer • System Design • medium

Design an ELT pipeline for a retail company that receives daily CSV dumps from 50 different vendors via SFTP. The data needs to be loaded into Snowflake for reporting.

#ELT #Cloud Architecture #Data Ingestion

Practice

Data Engineer • System Design • medium

You are extracting data from a third-party REST API that has a strict rate limit of 100 requests per minute. How do you design your Python extraction script to handle this?

#API Integration #Python #Rate Limiting

Practice

Data Engineer • Technical • hard

In a recent client project, you had to process a massive dataset using PySpark, but one of the tasks took significantly longer than the others. How do you identify and resolve data skew in Spark?

#PySpark #Performance Tuning #Data Skew

Practice

Data Engineer • Technical • medium

Explain how micro-partitions work in Snowflake. How would you choose a clustering key for a table containing billions of rows of transactional data?

#Snowflake #Architecture #Performance Optimization

Practice

Data Engineer • Technical • medium

You have an Apache Airflow DAG with 10 tasks. Task 5 fails intermittently due to an external API timeout. How do you handle this robustly?

#Airflow #Error Handling #Retries

Practice

Data Engineer • Technical • medium

What is a Broadcast Hash Join in Spark? When would you use it, and what are its limitations?

#Spark SQL #Joins #Optimization

Practice

Data Engineer • Technical • medium

How do you handle PII (Personally Identifiable Information) and PHI (Protected Health Information) in a data pipeline to ensure compliance with GDPR/HIPAA?

#Security #Compliance #Data Masking

Practice

Data Engineer • Technical • hard

You are running a PySpark job that keeps failing with an 'OutOfMemoryError: Java heap space'. What steps do you take to debug and fix this?

#PySpark #Troubleshooting #Memory Management

Practice

Data Engineer • Technical • easy

Explain the difference between a Star Schema and a Snowflake Schema. When would you recommend one over the other to a client?

#Data Warehousing #Dimensional Modeling

Practice

Data Engineer • Technical • medium

How do you implement CI/CD for data engineering pipelines? What tools do you use and what does the workflow look like?

#CI/CD #Git #Testing

Practice

Data Engineer • Technical • easy

In Python, what is the difference between a list comprehension and a generator expression? When would you use a generator in a data pipeline?

#Memory Management #Generators

Practice

Data Engineer • Technical • medium

What are the key features of Delta Lake, and how does it solve the limitations of traditional data lakes?

#Delta Lake #ACID Transactions #Databricks

Practice

Data Engineer • Technical • medium

What is a factless fact table? Provide a real-world business use case where you would implement one.

#Dimensional Modeling #Fact Tables

Practice

Data Engineer • Technical • medium

A client complains that a specific reporting query is taking 30 minutes to run. Walk me through your step-by-step approach to optimize this SQL query.

#Performance Tuning #Query Optimization

Practice

Data Engineer • Technical • medium

Data quality is a major focus at Deloitte. How do you implement automated data quality checks in your ETL pipelines?

#Data Quality #Testing #Great Expectations

Practice

Data Engineer • Technical • easy

Explain the difference between RANK(), DENSE_RANK(), and ROW_NUMBER() in SQL. Provide a brief example of when to use each.

#Window Functions

Practice

Data Engineer • Technical • medium

How do you handle schema evolution in a data lake environment when upstream source systems add, remove, or change the data types of columns?

#Schema Evolution #Parquet #Delta Lake

Practice

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