Java

When is an index not advantageous?

What are replication, partitioning, sharding — what are they?

What is a deadlock? How to avoid it?

Do you use any ORM? Have you used it? Why?

How have you optimized queries? How did you realize they were performing poorly?

Can you tell the advantages and disadvantages of ORM, and when would you use or not use it?

How does EXPLAIN work and what is the difference between EXPLAIN and EXPLAIN ANALYZE?

How to create an index on a large table in production without blocking and exceeding timeouts in Kubernetes?

What levels of transaction isolation do you know in relation to PostgreSQL?

What types of databases are there and what are they used for?

How did you deploy database changes to production? Did you use Liquibase?

How to solve the problem of long database migration with limited Kubernetes (liveness probe) time?

What are pessimistic and optimistic locking? How to obtain a pessimistic lock without changing the isolation level?

What indices do you know? How does a B-tree index work?

How would you perform a complex migration (adding a mandatory column to a table with 300 million records) using Liquibase?

There is a composite index on the fields name and username. Will the index work when querying WHERE username = ?

How to implement optimistic locking in code? What happens in case of a version conflict?

Kafka vs RabbitMQ — differences. How do consumer groups work in Kafka?

What are transactions? Explain the reasons for use and the properties of ACID.

Why might a scheduler ignore an index even if it exists?