10+ PEOL Interview Questions and Answers

AWS services used include S3, Redshift, Glue, EMR, and Lambda in a scalable and cost-effective architecture.

• AWS S3 for storing large amounts of data

• AWS Redshift for data warehousing and analytics

• AWS Glue for ETL processes

• AWS EMR for big data processing

• AWS Lambda for serverless computing

Use a SQL query with a subquery to find the 2nd most ordered item in a category.

• Use a subquery to rank items within each category based on the number of orders

• Select the item with rank 2 within each category

• Order the results by category and rank to get the 2nd most ordered item in each category

Spark submit command is used to submit Spark applications to a cluster

• Used to launch Spark applications on a cluster

• Requires specifying the application JAR file, main class, and any arguments

• Can set various configurations like memory allocation, number of executors, etc.

• Example: spark-submit --class com.example.Main --master yarn --deploy-mode cluster myApp.jar arg1 arg2

Developed a real-time data processing pipeline for analyzing customer behavior

• Designed and implemented data ingestion process using Apache Kafka

• Utilized Apache Spark for data processing and analysis

• Built data models and visualizations using tools like Tableau

• Implemented machine learning algorithms for predictive analytics

Developed a real-time data processing pipeline for analyzing customer behavior

• Designed and implemented data ingestion process using Apache Kafka

• Utilized Apache Spark for data processing and analysis

• Built data models and visualizations using tools like Tableau

• Implemented machine learning algorithms for predictive analytics

To configure a cluster for 100 TB data, consider factors like storage capacity, processing power, network bandwidth, and fault tolerance.

• Choose a distributed storage system like HDFS or Amazon S3 for scalability and fault tolerance.

• Select high-capacity servers with sufficient RAM and CPU for processing large volumes of data.

• Ensure high-speed network connections between nodes to facilitate data transfer.

• Implement data replication and backup strategies to prevent data loss.

• Cons...read more

Our current project architecture involves a microservices-based approach with data pipelines for real-time processing.

• Utilizing microservices architecture for scalability and flexibility

• Implementing data pipelines for real-time processing of large volumes of data

• Leveraging cloud services such as AWS or Azure for infrastructure

• Using technologies like Apache Kafka for streaming data

• Ensuring data quality and reliability through monitoring and testing

Static functions in OOP are functions that belong to the class itself, rather than to instances of the class.

• Static functions can be called without creating an instance of the class.

• They are commonly used for utility functions that do not require access to instance-specific data.

• Static functions are declared using the 'static' keyword in many programming languages.

• Example: In Java, a static function in a class can be called using ClassName.staticFunction().

Websockets are a communication protocol that allows for full-duplex communication between a client and a server over a single, long-lived connection.

• Websockets provide real-time, bi-directional communication between a client and a server.

• They are commonly used in applications that require instant updates, such as chat applications, online gaming, and financial trading platforms.

• Websockets use a persistent connection, unlike traditional HTTP requests which are stateless and re...read more

JWT stands for JSON Web Token, a compact and self-contained way for securely transmitting information between parties as a JSON object.

• JWT is composed of three parts: header, payload, and signature.

• Header typically consists of the type of token and the hashing algorithm being used.

• Payload contains the claims, which are statements about an entity and additional data.

• Signature is created by encoding the header, payload, a secret, and the algorithm specified in the header.

• JWTs c...read more

Polymorphism in OOPs allows objects of different classes to be treated as objects of a common superclass.

• Polymorphism allows methods to be called on objects of different classes that all inherit from a common superclass.

• It enables a single interface to be used for different data types or classes.

• Examples include method overriding in inheritance and method overloading within the same class.

I would structure the online shop with a user-friendly interface and easy navigation.

• Create a homepage with featured products and promotions

• Organize products into categories for easy browsing

• Include a search bar for quick product search

• Implement a shopping cart and checkout process

• Ensure mobile responsiveness for on-the-go shopping

• Include customer reviews and ratings for products

• Provide secure payment options

Yes, slow SQL queries can be optimized through various methods.

• Identify slow queries using tools like EXPLAIN or query logs

• Optimize queries by adding indexes, rewriting queries, or using query hints

• Consider denormalizing data or using caching mechanisms

• Monitor query performance regularly to identify bottlenecks