The interview process consisted of two stages:

1. A live coding interview with one developer. You were given a small portion of tasks, and upon finishing the first task, you received a new one.

2. A more technical interview with two engineers. Initially, they presented a simple concurrency task. Afterward, the discussion covered database theory, concurrency, and software design.

All interviewers were polite. They affirmed your answers, and you felt 100% certain about their correctness. However, one or two hours after the interview, you received the response: "Thank you for your time! Unfortunately, we can't proceed to the next steps. From successful candidates, we expect a deeper understanding of databases and concurrency." This was strange because you answered all questions regarding all topics, yet received such a response. You tried to contact HR, but received no reply.

Upon reading reviews for the company, you discovered that this situation is not unique. While the reasons remain unclear, it's advised not to spend your time with this company. They produce a great product but, for some reason, handle the recruitment process poorly.

--- Updated ---

HR response: "You are right; you were able to answer all questions correctly. Unfortunately, we require a deeper knowledge in the DB part and fewer mistakes in the coding part to offer more than a Junior position."

Regarding the database knowledge, there is nothing to comment on. In the development part, you did not recall the API for the BigDecimal class. This update may be helpful for some.

Thread blocking, DB indexing, transactions, isolation of transactions, pessimistic/optimistic locking, queues, service deployment, design patterns like:

• Circuit breaker
• Retry