Dun & Bradstreet Data Engineer Interview Questions and Answers

Q1. Pyspark, sql, Python.
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Q1. Python, dsa,PySpark
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Q1. Simple questions
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Q1. Windows function on sql
Ans. 
Window functions in SQL are used to perform calculations across a set of table rows related to the current row.
• Window functions are used to calculate values based on a set of rows related to the current row

• They do not cause rows to become grouped into a single output row like aggregate functions

• Common window functions include ROW_NUMBER(), RANK(), DENSE_RANK(), and NTILE()
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Q1. Pandas questions
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Q1. Asked regarding the previous project
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Apptitude test happen in first go it was quite easy

GD happen between 10 group member we have speak for sometime

Q1. Question on OOPS
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Q2. Quesion on SQL and python
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Aws, scala and cloud concept

Q1. Python question
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General Aptitude test and 3 Medium level coding questions

Q1. Sortr an array of 0,1
Ans. 
Sort an array of 0s and 1s
• Use a sorting algorithm like counting sort or two-pointer approach

• Count the number of 0s and 1s and then reconstruct the array

• Example: Input array = ['0', '1', '0', '1', '1'], Output array = ['0', '0', '1', '1', '1']
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Q2. Matrix traversal in spiral Manner
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Matrix traversal in spiral manner involves visiting each element of a matrix in a spiral order.
• Start by traversing the outermost layer of the matrix from top left to top right, then top right to bottom right, bottom right to bottom left, and finally bottom left to top left.

• Continue this process for the inner layers until all elements are visited.

• Keep track of the boundaries of the matrix to know when to switch directio
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Q1. Explain hadoop ecosystem
Ans. 
Hadoop ecosystem is a collection of open-source software tools used for distributed storage and processing of big data.
• Hadoop Distributed File System (HDFS) for storage

• MapReduce for processing

• Apache Hive for data warehousing

• Apache Pig for data analysis

• Apache Spark for real-time processing

• Apache HBase for NoSQL database

• Apache Kafka for real-time data streaming
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Q2. Explain YARN architecture
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YARN architecture is a resource management layer in Hadoop ecosystem for job scheduling and cluster resource management.
• YARN stands for Yet Another Resource Negotiator.

• It consists of ResourceManager, NodeManager, ApplicationMaster, and Container.

• ResourceManager manages resources and schedules applications.

• NodeManager runs on each node and manages resources available on that node.

• ApplicationMaster negotiates resources w...read more
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Q3. Hive external and internal tables
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Q4. Sort by and order by difference
Ans. 
Sort by is used to arrange data in a specific order, while order by is used to specify the sorting order in SQL queries.
• Sort by is used in programming languages to arrange data based on a specific criteria

• Order by is used in SQL queries to specify the sorting order of the result set

• Sort by is more commonly used in programming languages like Python, while order by is used in SQL queries
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Q5. Broadcast and accumulator
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Q6. Optimization techniques
Ans. 
Optimization techniques are methods used to improve the efficiency and performance of data processing.
• Use indexing to speed up data retrieval

• Implement caching to reduce redundant computations

• Utilize parallel processing for faster execution

• Optimize algorithms for better performance

• Use data compression techniques to reduce storage space
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Q1. It was a managerial round which was mostly around the project work and working experience in a team
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Q2. What was your role and responsisbility in the project
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Q3. Why is the approach of the project in this manner
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Q4. Few scenario based question
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Q1. Compensation and salary discussion
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Q1. What is pip in python
Ans. 
pip is a package manager for Python that allows you to install and manage libraries and dependencies.
• pip is used to install Python packages from the Python Package Index (PyPI)

• It can also be used to uninstall packages, upgrade packages, and list installed packages

• Example: 'pip install numpy' installs the numpy package
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Q2. Questions on join
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Leet Code Medium, string, list, tuple