Petronas Data Engineer Interview Questions and Answers

Q1. SQL table distributions.
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Q2. ADF switching questions?
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Q3. How do you optimize the performance?
Ans. 
Performance optimization in data engineering involves tuning queries, indexing, partitioning, and utilizing appropriate hardware.
• Tune queries by optimizing SQL code, using appropriate joins, and avoiding unnecessary operations.

• Utilize indexing to speed up data retrieval by creating indexes on frequently queried columns.

• Partition data to distribute it across multiple nodes or servers for parallel processing.

• Utilize appr...read more
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Q4. What is stored procedure?
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A stored procedure is a set of SQL statements that can be saved and reused in a database management system.
• Stored procedures are used to perform a specific task or set of tasks in a database.

• They can accept input parameters and return output parameters.

• Stored procedures can improve performance by reducing the amount of data sent between the database and the application.

• They can also enhance security by controlling acce...read more
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Q5. Ranking functions in SQL?
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Ranking functions in SQL are used to assign a rank to each row based on a specific criteria.
• Ranking functions include RANK(), DENSE_RANK(), and ROW_NUMBER()

• RANK() assigns a unique rank to each distinct row

• DENSE_RANK() assigns a unique rank to each distinct row without gaps

• ROW_NUMBER() assigns a unique sequential integer to each row
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Q6. Modelling questions.
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Asked Real Time Scenario to create Microservice for Train and Station information. The interviewer asked what are the properties needs to be considered for evaluating service.

Core Java 11 questions: Webservices, Improvement in JVM, Threads

Java 8: Asked to write a program based on Group By Scenario.

The interview lasts around 2 hrs.

Q1. Managerical round: Asked about current project details, The reason to join BH, Scenario based question on LinkedList vs ArrayList
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Q1. It was easy. The HR told about company policies
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Q1. LRU Cache Implementation
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Reverse a binary tree and few other technical questions

Q1. Data structure and Oops concepts were asked
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Q1. Technical round on projects that we have worked on and questions around that
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Q1. General HR questions
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Q1. More of like a general conversation with the center manager
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Q1. What is oops, explain them?
Ans. 
Object-oriented programming (OOP) is a programming paradigm that uses objects to represent and manipulate data.
• OOP is based on the concept of classes and objects.

• It allows for encapsulation, inheritance, and polymorphism.

• Encapsulation hides the internal details of an object and provides a public interface.

• Inheritance allows classes to inherit properties and methods from other classes.

• Polymorphism allows objects of diff...read more
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Q2. What is difference between interface and abstract class?
Ans. 
Interface defines only method signatures while abstract class can have method implementations.
• An interface can be implemented by multiple classes while a class can extend only one abstract class.

• An abstract class can have instance variables while an interface cannot.

• An abstract class can have constructors while an interface cannot.

• An abstract class can provide default implementations for some methods while an interface...read more
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Q3. What is difference between docker and kubernet?
Ans. 
Docker is a containerization platform while Kubernetes is a container orchestration tool.
• Docker is used to create, deploy, and run applications in containers.

• Kubernetes is used to manage and orchestrate multiple containers in a cluster.

• Docker provides a way to package and distribute applications in a portable manner.

• Kubernetes provides features like automatic scaling, load balancing, and self-healing.

• Docker is a lower-...read more
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Q4. What is event emitter in angular?
Ans. 
Event emitter is a class in Angular that allows communication between components.
• Event emitter is used to emit custom events in Angular.

• It allows communication between parent and child components.

• It can be used to pass data from child to parent component.

• It is a part of the @angular/core package.

• Example: @Output() eventEmitter = new EventEmitter();
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Q5. What is view encapsulation in angular?
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View encapsulation is a feature in Angular that allows for the creation of isolated components.
• View encapsulation ensures that styles defined in a component do not affect other components.

• There are three types of view encapsulation: Emulated, Native, and None.

• Emulated is the default and uses CSS to emulate shadow DOM.

• Native uses the browser's native shadow DOM implementation.

• None does not provide any view encapsulation
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Q6. How to communicate with components in angular?
Ans. 
Components in Angular can communicate with each other using @Input, @Output, and services.
• Use @Input to pass data from parent to child component

• Use @Output to emit events from child to parent component

• Use services to share data between components that are not directly related

• Use RxJS subjects to create a shared data stream between components
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2 question :

1. Find the longest common subsequence in 2 strings
2. find the 5th highest revenue from the table in last 28 days in a particular region

I was given a list of book, genre of books and books and rating of books . All list was of equal length n.

There were 2 methods which need to be implemented
1. get highest rating of book by genre . if rating are same then in lexographical order
2. update book rating by book name

Q1. These questions were basic
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Q2. There were lots of imaginative situation given and then I was asked to say what I would do in those situation
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Q1. Question as per my skill set from SQL, Unix, Power Center Mappings.
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Q1. In detail questions on skill sets and writing logic and flow diagram for one of the problem statement
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Q1. General discussion on expectations and the requirments
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Q1. Don't remember the exact questions
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First round was online assessment test with programming and aptitude games

Q1. Group Anagram question
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Q2. SQL question to get name of employee whose salary is greater than average salary of the department
Ans. 
SQL query to retrieve name of employee with salary greater than department average.
• Calculate average salary of department using GROUP BY clause

• Join employee and department tables using department ID

• Filter employees with salary greater than department average

• Select employee name
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