PwC Big Data Engineer Interview Questions, Process, and Tips

Q1. What is explode function ?
Ans. 
explode function is used in Apache Spark to split a column containing arrays into multiple rows.
• Used in Apache Spark to split a column containing arrays into multiple rows

• Creates a new row for each element in the array

• Syntax: explode(col: Column): Column

• Example: df.select(explode(col('array_column')))
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Some multiple choice, 2 sql and 2 python questions were asked

Q1. Tell me about you project
Ans. 
Developed a real-time data processing system for analyzing customer behavior
• Used Apache Kafka for streaming data ingestion

• Implemented data pipelines using Apache Spark for processing and analysis

• Utilized Elasticsearch for storing and querying large volumes of data

• Developed custom machine learning models for predictive analytics
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Q2. Optimising technique that you have used
Ans. 
I have used partitioning and indexing to optimize query performance.
• Implemented partitioning on large tables to improve query performance by limiting the data scanned

• Created indexes on frequently queried columns to speed up data retrieval

• Utilized clustering keys to physically organize data on disk for faster access
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Q1. Window partition question was asked
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Q2. Project related question
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Q1. Project related discussions
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Q2. Meduim level SQl and DSA
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Q1. This was data modelling round
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Q2. Design a uber data model
Ans. 
Uber data model design for efficient storage and retrieval of ride-related information.
• Create tables for users, drivers, rides, payments, and ratings

• Include attributes like user_id, driver_id, ride_id, payment_id, rating_id, timestamp, location, fare, etc.

• Establish relationships between tables using foreign keys

• Implement indexing for faster query performance
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Three sections are there 1) Aptitude Test 2) SQL 3) DSA

Q1. What is DSA , sorting , difference between array and linked list
Ans. 
DSA stands for Data Structures and Algorithms. Sorting is the process of arranging data in a particular order. Array is a data structure that stores elements of the same data type in contiguous memory locations, while linked list is a data structure that stores elements in nodes with pointers to the next node.
• DSA stands for Data Structures and Algorithms

• Sorting is the process of arranging data in a particular order

• Arra...read more
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Q2. Written a SQL query
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Q1. Coding question like add numbers
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Q2. Experience on your project
Ans. 
I have experience working on various data analysis projects, including market research, customer segmentation, and predictive modeling.
• Developed predictive models to forecast customer behavior and optimize marketing strategies

• Conducted market research to identify trends and opportunities for growth

• Performed customer segmentation analysis to target specific demographics with personalized marketing campaigns
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Q1. Power BI Difference between ALL() and ALLSELECTED()
Ans. 
ALL() ignores all filters in the query context, while ALLSELECTED() ignores only filters on columns in the visual.
• ALL() removes all filters from the specified column or table.

• ALLSELECTED() removes filters from the specified column or table, but keeps filters on other columns in the visual.

• Example: ALL('Table') would remove all filters on the 'Table' in the query context.

• Example: ALLSELECTED('Column') would remove filte...read more
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Q2. Excel Difference between COUNT() and COUNTA()
Ans. 
COUNT() counts only numeric values, while COUNTA() counts all non-empty cells.
• COUNT() counts only cells with numerical values.

• COUNTA() counts all non-empty cells, including text and errors.

• Example: COUNT(A1:A5) will count only cells with numbers, while COUNTA(A1:A5) will count all non-empty cells.
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Q1. Resume based questions like explain the projects that you have done.
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Q2. Sample dataset questions
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Q1. Project explaining
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Q2. Write code to generate csv file with note pad data
Ans. 
Code to generate a CSV file with notepad data
• Open a text file and read the data

• Parse the data and write it to a CSV file

• Use libraries like pandas in Python for easier CSV handling
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Maxium sub string and reverse a string

Basic English, Quants and Statistics

Easy, relevant to pandemic

Q1. Python, Tableau, SQL, Stats, ML, all questions easy to medium level
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Q1. Behavioural Questions
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Q2. Statistics Case Study
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