Tesco Site Engineer Interview Questions and Answers

Q1. What is the role of exception handling in programming, and how is the 'finally' block used in this context, as well as the process of throwing exceptions?
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Exception handling is crucial in programming to handle errors and ensure proper execution. The 'finally' block is used to clean up resources, and throwing exceptions allows for error propagation.
• Exception handling is used to manage errors and unexpected situations in a program.

• The 'finally' block is used to execute code that should always run, regardless of whether an exception is thrown or not.

• Throwing exceptions allo...read more
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Q2. What are the differences between SQL and NoSQL databases, and can you mention some NoSQL databases that you are familiar with?
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Q3. What are the ACID properties implemented in your project, and can you provide a brief overview of the CAP Theorem?
Ans. 
ACID properties ensure data integrity in transactions. CAP Theorem states that a distributed system can only guarantee two out of three: Consistency, Availability, Partition Tolerance.
• ACID properties: Atomicity, Consistency, Isolation, Durability

• Example: In a banking application, a transfer of funds should be atomic, consistent, isolated, and durable

• CAP Theorem: Consistency, Availability, Partition Tolerance - a distri...read more
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Q4. Database disaster recovery?
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Database disaster recovery involves strategies to restore data and maintain operations after a failure or data loss.
• Regular backups: Schedule daily or weekly backups to ensure data can be restored.

• Redundancy: Use replication to maintain copies of the database in different locations.

• Testing recovery plans: Regularly test disaster recovery plans to ensure they work effectively.

• Use of cloud services: Leverage cloud-based ...read more
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Q5. What is the difference between Comparable and Comparator in Java? And how to Implement in Collections.
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Comparable is an interface used for natural ordering, while Comparator is used for custom ordering in Java Collections.
• Comparable interface is used to define the natural ordering of objects. It is implemented by the class whose objects are to be sorted.

• Comparator interface is used to define custom ordering of objects. It is implemented by a separate class.

• To implement Comparable, the class needs to override the compare...read more
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Q6. Implementation of Generics in Java
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Generics in Java allow for creating classes, interfaces, and methods that operate on types parameterized at compile time.
• Generics provide type safety by allowing compile-time type checking.

• They enable code reusability and reduce the need for casting.

• Example: List<String> list = new ArrayList<>();
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Q1. Can you provide the code to reverse a string using recursion?
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Code to reverse a string using recursion
• Create a recursive function that takes a string as input

• Base case: if the string is empty or has only one character, return the string

• Recursive case: return the last character of the string concatenated with the result of calling the function on the substring excluding the last character
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Q2. How does object comparison work with specific fields?
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Object comparison with specific fields involves comparing values of selected fields between two objects.
• Object comparison can be done by comparing the values of specific fields in two objects.

• Fields can be selected based on unique identifiers or criteria for comparison.

• Example: Comparing the 'name' field of two person objects to check if they are the same.
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Q3. How does the distributed transactions being handled in a microservice?
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Distributed transactions in microservices involve using compensating transactions and event-driven architecture.
• Microservices typically use compensating transactions to maintain consistency across multiple services.

• Event-driven architecture can help in coordinating distributed transactions by using events to trigger actions in different services.

• Implementing distributed transactions in microservices requires careful de...read more
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Q4. Aggregator Pattern in Microservice
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Aggregator pattern is used in microservices architecture to combine multiple service responses into a single response.
• Aggregator pattern helps in reducing the number of client requests by combining multiple service responses.

• It can be implemented using a separate service or within an existing service.

• Example: A shopping website aggregating product information from different microservices like inventory, pricing, and re...read more
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Q5. What is the implementation of the factory design pattern?
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Factory design pattern is a creational pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.
• Factory method pattern defines an interface for creating objects, but lets subclasses decide which class to instantiate.

• It promotes loose coupling by eliminating the need to bind application-specific classes into the code.

• Example: A car m...read more
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Q6. What is indexing in a database, and what data structures are commonly used for indexing?
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Indexing in a database is a technique to improve the speed of data retrieval by creating a data structure that allows for quick lookup.
• Indexing involves creating a separate data structure that contains pointers to the actual data in the database.

• Common data structures used for indexing include B-trees, hash tables, and binary search trees.

• Indexes can be created on one or multiple columns in a database table to speed up...read more
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Q7. What is your approach to designing a system capable of handling thousands of requests?
Ans. 
My approach involves using load balancing, caching, asynchronous processing, and horizontal scaling.
• Implement load balancing to distribute requests evenly across multiple servers.

• Utilize caching mechanisms to store frequently accessed data and reduce response times.

• Use asynchronous processing for long-running tasks to free up resources for handling more requests.

• Implement horizontal scaling by adding more servers to ha...read more
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Q8. What is the CQRS pattern in microservices?
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CQRS pattern in microservices separates read and write operations for improved scalability and performance.
• CQRS stands for Command Query Responsibility Segregation

• It separates the read and write operations into two different models

• Write operations update the data store, while read operations query a separate data store

• CQRS can improve performance and scalability by allowing each model to be optimized for its specific t...read more
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Q9. What is the role of API Gateway in microservices architecture?
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API Gateway acts as a single entry point for all client requests in a microservices architecture.
• API Gateway handles authentication, authorization, rate limiting, and routing of requests to appropriate microservices.

• It helps in decoupling client applications from individual microservices, providing a more flexible and scalable architecture.

• API Gateway can also perform tasks like request/response transformation, logging...read more
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Q10. Write SQL query to fetch data from two tables using joins?
Ans. 
SQL query to fetch data from two tables using joins
• Use the JOIN keyword to combine rows from two tables based on a related column

• Specify the columns to select from each table in the SELECT statement

• Use the ON keyword to specify the join condition
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Q1. Design principles for Low Level Architecture
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Low level architecture design principles focus on optimizing performance, efficiency, and resource utilization.
• Optimize for performance by minimizing latency and maximizing throughput

• Efficiently utilize resources such as memory, CPU, and network bandwidth

• Design for scalability and flexibility to accommodate future growth

• Use modular and reusable components to promote maintainability and code reusability

• Consider security...read more
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Q2. Mvcc architecture
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Q3. Kafka Architecture
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It was basically two leetcode Questions Mainly from array with some algorithm required to apply and other from LinkedList.

Q1. First the discussion was mainly on Projects you have worked on for first 20 minutes.
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Q2. Then was given to Design a chat application basically a High Level. Interviewer was friendly and prompt listener.
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Q1. Very Detailed Project Discussion and Scenario based Questions basically your achievements in detail.
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Q2. Then some Implementation questions related to designing and Java based and Kafka based.
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Q1. CTC Discussion and Expectations plus Notice period and other documents.
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Q1. Flood fill algorithm, other problems and technical questions
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Q2. Flood fill algorithm Other rech questions
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Water bill management system
Flood fill algo

2 coding problems.

One is on Hasmap

second one is on Tree

Q1. Pair programming Round
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Q2. One problem step by step solving with unit test cases maintaining time complexity and space complexity.
Ans. 
Step-by-step problem-solving with unit tests, focusing on time and space complexity.
• Identify the problem clearly, e.g., finding the maximum number in an array.

• Choose an efficient algorithm, e.g., O(n) time complexity for a linear search.

• Implement the solution in code, ensuring clarity and maintainability.

• Write unit tests to cover edge cases, e.g., empty array, single element.

• Analyze space complexity, ensuring minimal a...read more
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Q1. High level Design
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Q1. Techno - Managerial
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Q1. Normal discussion benefits and salary
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Q1. Write design for URL sortner
Ans. 
Design a URL shortener system
• Use a unique identifier for each long URL to generate a short URL

• Store the mapping of short URL to long URL in a database

• Implement a redirect mechanism to redirect short URLs to their corresponding long URLs

• Consider scalability and performance while designing the system
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Q2. Program to detect cycle on linked list
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Mostly dynamic programming and tree based programs

Q1. Coding Coordinate geometry problem
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Q2. Coding on trees
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Q1. HLD / LLD , Java technical questions
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Q2. Pair programming
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Q1. Asked about resume and then some questions on Linkedlist, Stack
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Q2. Java garbage collection
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Q3. What is Bean in Spring
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A bean in Spring is a Java object that is instantiated, assembled, and managed by the Spring IoC container.
• Beans are defined in the Spring configuration file using XML or annotations.

• Beans are singleton by default but can be configured as prototype.

• Beans can have dependencies injected by the container.

• Example: @Component annotation in Spring creates a bean.

• Example:
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