10+ Chill Tech Engineers Interview Questions and Answers

The output will be the literal string of the variable, without any variable interpolation.

• When a variable is echoed in single quotes, it is treated as a literal string.

• No variable interpolation or special characters are interpreted.

• The output will include the variable name itself, not its value.

Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

• Abstract class can have constructors, fields, and methods, while interface cannot have any of these.

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Abstract classes are used to provide a common base for multiple classes, while interfaces are used to define a contract for classes to implement.

• Example: Abstract class 'Shape' with ...read more

The final class and method are used to prevent inheritance and method overriding respectively.

• Final class: A final class cannot be subclassed. It is often used for utility classes or classes that should not be extended.

• Final method: A final method cannot be overridden by subclasses. It is used to prevent modification of a method's behavior in subclasses.

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 focuses on 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 different classes to be treated as objects of a common supercl...read more

Database queries involve retrieving, updating, and manipulating data stored in a database.

• Database queries are used to retrieve specific data from a database based on certain criteria.

• Queries can also be used to update existing data or insert new data into the database.

• SQL (Structured Query Language) is commonly used to write database queries.

• Examples of database queries include SELECT, INSERT, UPDATE, and DELETE statements.

Find duplicate numbers in an array of strings.

• Iterate through the array and keep track of the count of each number using a hash map.

• If the count of a number is greater than 1, it is a duplicate.

• Return the list of duplicate numbers.

The HAVING clause is used in MySQL to filter the results of a GROUP BY query based on a condition.

• The HAVING clause is similar to the WHERE clause, but it operates on grouped rows rather than individual rows.

• It is used in conjunction with the GROUP BY clause.

• The HAVING clause is used to filter the results of a GROUP BY query based on a condition that applies to the grouped rows.

• It is typically used to specify conditions on aggregate functions like COUNT, SUM, AVG, etc.

• The HAV...read more

OOP Concepts refer to the principles of Object-Oriented Programming, including encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (object).

• Inheritance: Allowing a class to inherit properties and behavior from another class.

• Polymorphism: The ability for objects of different classes to respond to the same message in different ways.

• Abstraction: Hiding the complex implementation details an...read more

Postgres Architecture is a client-server model with a multi-process approach.

• Postgres uses a multi-process approach with a master process and worker processes.

• The master process manages shared memory and worker processes handle client connections.

• Postgres also has a background process for maintenance tasks and a WAL writer for data durability.

• Postgres supports ACID transactions and has a query planner for optimizing queries.

• Postgres also has a storage manager for managing dis...read more

The question covers topics related to object-oriented programming, SQL joins, and previous projects.

• Demonstrate understanding of object-oriented programming principles such as encapsulation, inheritance, and polymorphism

• Explain how SQL joins work and demonstrate ability to write complex join queries

• Discuss previous projects worked on, highlighting key achievements and challenges faced

Apache Joins js performance

• Apache joins are used to combine data from two or more tables based on a related column between them

• Joins in Apache Spark can be performed using functions like join(), crossJoin(), etc.

• Optimizing performance in Apache Spark involves tuning parameters like partitioning, caching, and parallelism

ACID property ensures that database transactions are processed reliably.

• ACID stands for Atomicity, Consistency, Isolation, and Durability.

• Atomicity ensures that a transaction is treated as a single unit of work, either all or none of its operations are executed.

• Consistency ensures that a transaction brings the database from one valid state to another.

• Isolation ensures that concurrent transactions do not interfere with each other.

• Durability ensures that once a transaction is c...read more