How Microservices Stay Consistent: The Saga Pattern (With an Example)

How do microservices stay consistent when a single order touches four different services — each with its own database? The answer is the saga pattern, and it's a favourite in system design interviews. In about 10 minutes we build it up from scratch with one beginner-friendly example: ordering a laptop across Order, Inventory, Payment, and Shipping. We walk the happy path, then break shipping and watch the compensating transactions undo everything in reverse. Even if this is completely new to you, by the end it will click.

What you'll learn:
• The problem: no shared transaction across microservices (and why two-phase commit doesn't scale)
• What a saga is: local transactions, each with a compensating "undo" action
• The happy path — ordering a laptop, step by step
• Compensating transactions — undoing in reverse when a step fails
• Choreography (event-driven, no central boss)
• Orchestration (a central conductor)
• Choreography vs orchestration — which to choose
• Key challenges: isolation, idempotency, observability
• Saga in code — steps paired with compensations
• When to use a saga (and when a plain ACID transaction is enough)

Practice these out loud with mock interviews, spaced repetition, and 500+ curated questions at https://prepforge.net

Chapters:
00:00 The Saga Pattern Explained
00:51 The Problem
01:46 1. What Is the Saga Pattern
02:36 2. The Happy Path
03:24 3. Compensating Transactions
04:19 4. Choreography
05:13 5. Orchestration
06:02 6. Choreography vs Orchestration
06:48 7. Key Challenges
07:44 8. Saga in Code
08:28 9. When to Use Saga
09:26 You're Saga-Ready

New to the channel? We've also broken down Kafka, RabbitMQ, Amazon SQS, and bloom filters. Subscribe for the full interview-prep series.

#SagaPattern #Microservices #SystemDesign #InterviewPrep #DistributedSystems