In the current scenario for a backend engineer, with programming skills we need to answer some system-related questions as well so the interviewer will check the knowledge of system design and optimization as well.
Here are some common software engineer interview questions for backend developers:
- What is a database index and how does it improve the performance of a database? [Brief Answer]
- How do you design a RESTful API?
- What is a stack and how does it work?
- How do you implement a connection pool in a backend application?
- How do you design a distributed system?
- What is a database transaction and how does it ensure data integrity?
- How do you design a rate limiter?
- How do you implement a job queue?
- How do you handle horizontal scaling in a backend application?
- What is a cache and how does it work?
These questions are designed to test your knowledge of fundamental backend concepts and design patterns. It is important to be able to explain these concepts clearly and provide examples of how you have used them in your past projects.
Below is the answer to the above question, but you can prepare for this question based on your problem-solving skills, and the projects which you did earlier.
Question 1: What is a database index and how does it improve the performance of a database?
Answer: A database index is a data structure that improves the speed of data retrieval operations on a database table. It allows the database to quickly find and retrieve specific rows based on the indexed columns.
Question 2: How do you design a RESTful API?
Answer: To design a RESTful API, you should follow the principles of REST (Representational State Transfer), which include using HTTP methods (e.g. GET, POST, PUT, DELETE) to perform actions on resources, using a clear and consistent URL structure, and returning appropriate HTTP status codes.
Question 3: How do you design a distributed system?
Answer: A stack is a Last-In-First-Out (LIFO) data structure that supports two main operations: push (add an element to the top of the stack) and pop (remove the top element from the stack). It can be implemented using an array or a linked list.
Question 4: How do you implement a connection pool in a backend application?
Answer: To implement a connection pool in a backend application, you can create a pool of pre-established connections to a database or other resources. When a request for a connection is received, the pool can return an available connection from the pool instead of creating a new one.
Question 5: How do you design a distributed system?
Answer: To design a distributed system, you should consider factors such as scalability, fault tolerance, and data consistency. You can use techniques such as load balancing, replication, and consensus algorithms to design a distributed system that meets your requirements.
Question 6: What is a database transaction and how does it ensure data integrity?
Answer: A database transaction is a unit of work that is either completes fully or not at all. It ensures data integrity by rolling back any changes if an error occurs during the transaction.
Question 7: How do you design a rate limiter?
Answer: To design a rate limiter, you can use a counter that increments every time a request is made and decrements over time. If the counter exceeds a certain threshold, the rate limiter can block or throttle the request.
Question 8: How do you implement a job queue?
Answer: To implement a job queue, you can use a message queue system such as RabbitMQ or Kafka to store and process jobs asynchronously. The backend application can add jobs to the queue and workers can consume and execute the jobs.
Question 9: How do you handle horizontal scaling in a backend application?
Answer: To handle horizontal scaling in a backend application, you can add more instances of the application to handle an increase in traffic. This can be done manually or automatically using a load balancer.
Question 10: What is a cache and how does it work?
Answer: A cache is a temporary storage area that holds frequently accessed data to improve the performance of an application. It stores data in memory or on disk and serves requests for data from the cache if it is available, otherwise, it retrieves the data from the original source.
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