[Solved] You design a microservice that consumes events from a message queue.... Which approach best balances scalability and correctness? | Microservices

Microservices - Event-Driven Architecture

You design a microservice that consumes events from a message queue. To ensure idempotency, you decide to store processed event IDs in a database. Which approach best balances scalability and correctness?

AStore event IDs in a centralized database with unique constraints

BStore event IDs in a local in-memory cache only

CIgnore event IDs and rely on message queue retries

DProcess events multiple times and fix duplicates later

Step-by-Step Solution

Solution:

Step 1: Evaluate local cache approach
Local cache is fast but not shared across instances, causing duplicates in distributed systems.
Step 2: Evaluate centralized DB with unique constraints
A centralized database with unique event ID constraints ensures correctness and scales with proper design.
Step 3: Evaluate ignoring IDs or fixing later
Ignoring IDs or fixing duplicates later risks data inconsistency and is not reliable.
Final Answer:
Store event IDs in a centralized database with unique constraints -> Option A
Quick Check:
Central DB + unique IDs = scalable correctness [OK]

Quick Trick: Use centralized DB with unique keys for idempotency [OK]

Common Mistakes:

MISTAKES

Using only local cache in distributed systems
Ignoring event IDs completely
Accepting duplicates to fix later

Master "Event-Driven Architecture" in Microservices

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Arch Try Challenge Design Recall Scale

More Microservices Quizzes

Which approach best balances scalability and correctness?

Step 1: Evaluate local cache approach

Step 2: Evaluate centralized DB with unique constraints

Step 3: Evaluate ignoring IDs or fixing later

Final Answer:

Quick Check:

Want More Practice?