Java

SQL task: list user IDs and the number of their orders with status COMPLETED, including users with zero such orders.

How does Spring build the process of creating beans from the moment the application starts? How do auto-configurations and conditional annotations work?

Tell about the N+1 problem in JPA/Hibernate, when it occurs and how it is solved.

What types of indexes do you know in PostgreSQL? Tell about B-tree index, how it is arranged. What is a GIN index?

List the transaction isolation levels and briefly explain their purposes.

Tell us about your work experience, key achievements, and technology stack

What is Kafka Streams, how does it differ from the usual Kafka operation scheme?

How does Spring behave when calling a method of another bean with @Transactional(propagation = REQUIRES_NEW) from a method with default propagation? What happens to the parent transaction?

Have you encountered cyclic dependencies? How to deal with them?

Tell me about the transaction mechanism in Spring, how it is implemented, and its limitations.

What is inversion of control (IoC), how is this principle implemented, and what is it used for?

Tell about working with Kubernetes: what is the difference between liveness probe and readiness probe? Why are there two resource requests and limits?

Java task: given an int[] array, form two lists — only unique and only duplicates.

Java Streams task: sort a Map<String, Integer> by value using streams.

Tell about the types of delivery guarantees in Kafka, how they differ, and when to use which.

How to ensure exactly-once semantics in Kafka? How is producer idempotency technically ensured?

Tell me about gRPC: how it works, what are its advantages over REST?

Tell me about the SAGA pattern, the two types — orchestration and choreography, and how do they differ?