Virtusa Consulting Services Senior Data Engineer Interview Questions and Answers

Platform - Hackerank
Duration - 2 Hours
Topics - Spark and SQL

Q1. What are the common file formats used in data storages? Which one is best for compression?
Ans. 
Common file formats used in data storages include CSV, JSON, Parquet, Avro, and ORC. Parquet is best for compression.
• CSV (Comma-Separated Values) - simple and widely used, but not efficient for large datasets

• JSON (JavaScript Object Notation) - human-readable and easy to parse, but can be inefficient for storage

• Parquet - columnar storage format that is highly efficient for compression and query performance

• Avro - efficie...read more
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Q2. SQL Problem - Given the empoyee attendance table, write a query to print the employees who is abscent for more than cosecutive 10 days in their tenure.
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Q3. Given the list of words, write the Python program to print the most repeating substring out of all words.
Ans. 
Python program to find the most repeating substring in a list of words.
• Iterate through each word in the list

• Generate all possible substrings for each word

• Count the occurrences of each substring using a dictionary

• Find the substring with the highest count
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Q1. How do you utilize the enhanced optimization option in AWS Glue?
Ans. 
Enhanced optimization in AWS Glue improves job performance by automatically adjusting resources based on workload
• Enhanced optimization in AWS Glue automatically adjusts resources like DPUs based on workload

• It helps improve job performance by optimizing resource allocation

• Users can enable enhanced optimization in AWS Glue job settings
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Q2. What are the best practices for optimizing querying in Amazon Redshift?
Ans. 
Optimizing querying in Amazon Redshift involves proper table design, distribution keys, sort keys, and query optimization techniques.
• Use appropriate distribution keys to evenly distribute data across nodes for parallel processing.

• Utilize sort keys to physically order data on disk, reducing the need for sorting during queries.

• Avoid using SELECT * and instead specify only the columns needed to reduce data transfer.

• Use AN...read more
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Q1. Adf,etl,python,adb
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Q1. What is scd type 2?
Ans. 
SCD type 2 is a method used in data warehousing to track historical changes by creating a new record for each change.
• SCD type 2 stands for Slowly Changing Dimension type 2

• It involves creating a new record in the dimension table whenever there is a change in the data

• The old record is marked as inactive and the new record is marked as current

• It allows for historical tracking of changes in data over time

• Example: If a cust...read more
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Q2. Pyspark question read CSV from folder and add column in each csv file and write it to different location.
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Q1. Explain about yourself.
Ans. 
I am a Senior Data Engineer with 5+ years of experience in designing and implementing data pipelines for large-scale projects.
• Experienced in ETL processes and data warehousing

• Proficient in programming languages like Python, SQL, and Java

• Skilled in working with big data technologies such as Hadoop, Spark, and Kafka

• Strong understanding of data modeling and database management

• Excellent problem-solving and communication sk
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Q2. Explain about your current project.
Ans. 
Developing a real-time data processing system for analyzing customer behavior on e-commerce platform.
• Utilizing Apache Kafka for real-time data streaming

• Implementing Spark for data processing and analysis

• Creating machine learning models for customer segmentation

• Integrating with Elasticsearch for data indexing and search functionality
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Q3. Big data concept
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Q4. Spark related questions
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Q1. Tell about experience
Ans. 
I have over 5 years of experience in data engineering, working with large datasets and implementing data pipelines.
• Developed and maintained ETL processes to extract, transform, and load data from various sources

• Optimized database performance and implemented data quality checks

• Worked with cross-functional teams to design and implement data solutions

• Utilized tools such as Apache Spark, Hadoop, and SQL for data processing

• ...read more
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Q2. What would you do when you are given a new task to do
Ans. 
I would start by understanding the requirements, breaking down the task into smaller steps, researching if needed, and then creating a plan to execute the task efficiently.
• Understand the requirements of the task

• Break down the task into smaller steps

• Research if needed to gather necessary information

• Create a plan to execute the task efficiently

• Communicate with stakeholders for clarification or updates

• Regularly track prog
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Normal aptitude test

Q1. Technical discussion on big data and some programing problem
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Q1. 2nd technical discussion based on project, big data and python
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Q1. Normal HR discussion and salary negotiation
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