Testbook.com Data Engineer Interview Questions and Answers

Q1. SQL queries , python pandas and numpy , power bi related questions
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Q1. Previous experience, skills and expertise
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Sql, numpy, pandas, dictionary, pandas group by, merging

Q1. Normal questions
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Q1. Explain request lifecycle in rails?
Ans. 
Request lifecycle in Rails involves routing, controller actions, rendering views, and responding to the client.
• 1. Request comes in through the browser or API endpoint.

• 2. Rails router determines which controller and action to route the request to.

• 3. Controller action processes the request, interacts with the model, and prepares data for the view.

• 4. View template is rendered with the data from the controller.

• 5. Response ...read more
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Q2. Code Merge Sort using Ruby
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Implement Merge Sort algorithm in Ruby
• Divide the array into two halves recursively

• Merge the sorted halves back together

• Use a helper method to merge the two halves
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Q1. What is List comprehension? Print Fibonacci series in python.
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List comprehension is a concise way to create lists in Python. Fibonacci series can be printed using list comprehension.
• List comprehension is a compact way to create lists in Python by iterating over an iterable object.

• Fibonacci series can be generated using list comprehension by defining the series logic within the comprehension.

• Example: fibonacci = [0, 1] + [fibonacci[i-1] + fibonacci[i-2] for i in range(2, 10)]
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Q1. You have two table. Employee and salary. Join the table and fetch the 3rd highest salary
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Customer segmentation on Sales Data

Q1. Psychological questions
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Round duration - 120 minutes
Round difficulty - Easy

It was a mix of mathematical aptitude, logical ability, and puzzles along with 2 programming questions of easy and medium level. Time was enough and no sectional time was present. 1-2 MCQs on SQL were also present.

This round was immediately followed by an SHL aptitude test which was basically a quick limited time check of your verbal ability and math because many questions were to be done in 1 hour.

Q1. 
Boolean Matrix Transformation Challenge
Given a 2-dimensional boolean matrix mat of size N x M, your task is to modify the matrix such that if any element is 1, set its entire row and column to 1. Specifi...read more
Ans. 
Modify a boolean matrix such that if any element is 1, set its entire row and column to 1.
• Iterate through the matrix and mark rows and columns to be modified

• Use additional arrays to keep track of rows and columns to be modified

• Update the matrix in-place based on the marked rows and columns
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Round duration - 60 minutes
Round difficulty - Easy

It was an online video interview round on HackerEarth with simultaneous code option. It was mostly justifying your resume in the first 15 minutes. After that OOPS was majorly asked. Basics of programming including questions on STL were asked. A class which required inheritance was asked by the interviewer to write. I was helped by the interviewer if i got stuck somewhere, Some questions on implementation of hashmaps and priority queues were also asked. A puzzle was asked which luckily struct to me at that moment.

Q1. What's your experience?
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Q2. Don't you have Data Science experience?
Ans. 
No, I don't have direct Data Science experience.
• However, I have worked with data extensively in my previous roles as a Data Analyst.

• I have experience in data cleaning, data visualization, and statistical analysis.

• I am also familiar with programming languages such as Python and R, which are commonly used in Data Science.

• I am willing to learn and expand my skills in Data Science if given the opportunity.
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