Java

How to create a transaction manually without the @Transactional annotation?

If memory consumption increases in production, where should the investigation start?

Name the parameters of the @Transactional annotation.

What is the purpose of TreeMap?

Design task: The Like service writes likes to Kafka, and the Dashboard service should calculate the post ratings. How to establish interaction?

Have you ever used window functions in PostgreSQL?

What stages of software development and implementation were in your team?

Senior

СБЕР

Is a primitive object field stored in the heap or in the stack?

What work format do you consider and from which city do you plan to work?

Why was reporting built on PostgreSQL under a load of ~2000 RPS? Why not use OLAP instead of OLTP for reporting?

Senior

СБЕР

What is the main problem with the chosen solution structure? - Hard initialization of final fields - The structure does not guarantee the uniqueness of services in the cache - Service search complicates testing - No usage template. Strategy of flexibility. - Service locator complicates debugging Code: public class CarMaintenanceReminder { private final ServiceLocator serviceLocator; private final ReminderCache reminderCache; public CarMaintenanceReminder() { this.serviceLocator = new ServiceLocator(); this.reminderCache = new ReminderCache(); } public Reminder getOilChangeReminder(String carId) { Reminder reminder = reminderCache.getReminder(carId); if (reminder == null) { reminder = serviceLocator.getService(ReminderService.class).createOilChangeReminder(carId); reminderCache.addReminder(reminder); } return reminder; } } class ServiceLocator { public <T> T getService(Class<T> serviceClass) { return serviceClass.cast(generateService(serviceClass)); } private Object generateService(Class<?> serviceClass) { if (serviceClass == ReminderService.class) { return new ReminderService(); } return null; } } class Reminder { private final String carId; public Reminder(String carId) { this.carId = carId; } } class ReminderService { public Reminder createOilChangeReminder(String carId) { return new Reminder(carId); } } class ReminderCache { private final Map<String, Reminder> cache; public ReminderCache() { this.cache = new HashMap<>(); } public Reminder getReminder(String carId) { return cache.get(carId); } public void addReminder(Reminder reminder) { cache.put(reminder.getCarId(), reminder); } }

In which case does a write to disk occur in the database?

Tell us about Stream API — what it is and how you use it.

What types of sharding exist? Describe the main approaches.

Senior

Ozon Финтех

Tell us about yourself and your experience.

Senior

Т-Банк

Have you had experience working with the Aerospike database?

Name three examples of terminal operations in the Stream API

Senior

Альфа-Банк

How can interaction between classes be represented using abstraction?

Does Kafka topic have FIFO property?

Senior

СБЕР

The scheduler takes records from the table, two pods simultaneously took one record — how to solve the problem?