iEnergizer Applications Engineer Interview Questions and Answers

Indexes are data structures that improve the speed of data retrieval operations on a database table.

• Indexes are created on columns in a database table to quickly retrieve rows matching a certain condition.

• They can be unique, allowing only unique values to be stored in the indexed column.

• Examples include primary keys, foreign keys, and indexes on frequently queried columns.

The pillars of object oriented programming are encapsulation, inheritance, and polymorphism.

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

• Inheritance: Allowing a new class to inherit properties and behavior from an existing class.

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

Interfaces are used to define contracts for classes to implement, while abstract classes can provide partial implementation.

• Interfaces can only have abstract methods and cannot have any implementation, while abstract classes can have both abstract and concrete methods.

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

• Interfaces are used to achieve multiple inheritance in Java, while...read more

Data warehouse is a centralized repository for storing and analyzing data from various sources to support decision-making processes.

• Data warehouse stores historical data from different sources for analysis

• It is used for reporting, querying, and data mining

• Data is structured in a way that makes it easier to query and analyze

• Examples: Amazon using data warehouse to analyze customer behavior, sales trends

• Data warehouse he...read more