Decision Point Data Engineer Interview Questions and Answers

Q1. What is coalesce
Ans. 
Coalesce is a function used to return the first non-null value in a list of expressions.
• Coalesce function is commonly used in SQL to handle null values.

• It takes multiple arguments and returns the first non-null value.

• Example: COALESCE(column1, column2, 'default') will return the value of column1 if not null, else column2, and if both are null, it will return 'default'.
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Q2. What is repartition
Ans. 
Repartition is the process of redistributing data across partitions in a distributed system.
• Repartitioning helps in balancing the workload and improving performance in distributed computing environments.

• It involves moving data between partitions based on certain criteria such as key values or hash functions.

• Repartitioning can be done in Spark using operations like repartition() or coalesce().
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Q1. Non repeatable character
Ans. 
A non repeatable character is a character that appears only once in a given string.
• Iterate through the string and count the frequency of each character

• Identify the characters that have a frequency of 1

• Return the first non repeatable character found
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Q2. Sort list without sort method
Ans. 
Sort list without using sort method
• Create a custom sorting function using loops

• Compare each element with every other element to determine the correct order

• Swap elements based on the comparison results
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Two coding questions, one is easy and the other is difficult. Who solved 2nd question was shortlisted for an interview.

Q1. Introduce yourself—questions from OS, DBMS, DSA, Project, and one coding problem.
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Q1. Maximal rectangal
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Q2. Loop in linked list
Ans. 
Loop in linked list is a situation where a node points to a previous node in the list, creating an infinite loop.
• Check for loops using Floyd's cycle detection algorithm

• Use two pointers, one moving twice as fast as the other, to detect a loop

• If the fast pointer catches up to the slow pointer, there is a loop
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Q1. Basic hr question regarding your project and all
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Q2. He was more interested in what is my thinking pattern
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Aptitude test was divided into 3 parts and was not a typical quant, logical question it was more of an application based questions

Q1. What do you understand about the company?
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Q1. Mostly behavioural and situation based questions.
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Q1. OOps, C#, MVC, WEBAPI, Azure
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Q2. Multiple inheritance concept in OOPs?
Ans. 
Multiple inheritance allows a class to inherit attributes and methods from more than one parent class.
• In multiple inheritance, a class can inherit from two or more parent classes.

• It can lead to the Diamond Problem where a class inherits from two classes that have a common ancestor.

• Languages like C++ support multiple inheritance.

• Example: class ChildClass : public ParentClass1, public ParentClass2 {}
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Q3. What is interface?
Ans. 
An interface in software development defines a contract for classes to implement, specifying methods and properties that must be included.
• Interfaces in programming languages like Java, C#, and TypeScript allow for multiple inheritance by defining a set of methods that a class must implement.

• Interfaces are used to enforce a common structure across different classes, promoting code reusability and maintainability.

• Example...read more
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Create Crud operation using angular with API.

Q1. Mostly on your experience. Azure, .net core, microservices.
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Q2. Coding round with basic programming questions. Easy level.
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