Event sourcing pattern in Microservices - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

What is the primary benefit of using event sourcing in microservices?

Consider a microservices system that uses event sourcing. What is the main advantage of this pattern?

A It stores the current state only, reducing storage needs.

B It guarantees zero network latency between services.

C It eliminates the need for any database in the system.

D It allows reconstructing past states by replaying events.

💡 Hint

Think about how event sourcing handles data changes over time.

Event sourcing stores all changes as events, allowing the system to rebuild any past state by replaying these events.

❓ Architecture

intermediate

Which component is essential in an event sourcing architecture?

In an event sourcing system, which component is responsible for storing all the events?

A Event Store

B Command Handler

C Read Model

D API Gateway

💡 Hint

Think about where the system keeps the history of all changes.

The Event Store is the component that stores all events in the system, acting as the source of truth.

❓ scaling

advanced

How does event sourcing help with scaling read operations in microservices?

In a microservices system using event sourcing, how can read operations be scaled efficiently?

A By replaying events on demand for every read request.

B By blocking writes during heavy read traffic.

C By using separate read models built from events for queries.

D By storing all data in a single monolithic database.

💡 Hint

Consider how read models can be optimized separately from writes.

Event sourcing allows building specialized read models from events, which can be scaled independently to handle queries efficiently.

❓ tradeoff

advanced

What is a common tradeoff when using event sourcing in microservices?

Which of the following is a typical downside of adopting event sourcing?

A Increased complexity in rebuilding current state from events.

B Immediate consistency without eventual consistency concerns.

C Simpler debugging due to fewer stored data points.

D No need for backups because events are immutable.

💡 Hint

Think about the effort needed to get the current state from stored events.

Event sourcing requires replaying events to rebuild state, which adds complexity and can impact performance.

❓ estimation

expert

Estimate the storage growth in an event sourcing system over time.

A microservice using event sourcing records 1000 events per minute. Each event is 1 KB in size. Estimate the storage needed after 1 year (assume 365 days).

A About 525 TB

B About 525 GB

C About 525 MB

D About 525 KB

💡 Hint

Calculate total events per year and multiply by event size.

1000 events/min × 60 min/hr × 24 hr/day × 365 days = 525,600,000 events. Each event is 1 KB, so total storage ≈ 525,600,000 KB ≈ 525 GB.