Saga pattern for distributed transactions in Microservices - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Saga pattern in distributed transactions?

The Saga pattern breaks a large transaction into smaller, independent steps called sagas. Each step updates data and publishes an event. If a step fails, compensating actions undo previous steps to keep data consistent.

beginner

How does the Saga pattern handle failures in a distributed system?

When a step in the saga fails, the pattern triggers compensating transactions that reverse the effects of previous successful steps, ensuring the system returns to a consistent state.

intermediate

What are the two main coordination styles of the Saga pattern?

1. Choreography: Each service listens for events and decides when to act. 2. Orchestration: A central coordinator tells each service what to do next.

intermediate

Why is the Saga pattern preferred over distributed two-phase commit in microservices?

Because it avoids locking resources for long times, improves scalability, and fits better with asynchronous communication common in microservices.

beginner

What is a compensating transaction in the Saga pattern?

A compensating transaction is an action that reverses the effects of a previously completed step in the saga to maintain data consistency after a failure.

What does a compensating transaction do in the Saga pattern?

A Reverses a previous successful step

B Commits the current transaction

C Starts a new saga

D Locks resources for consistency

Compensating transactions undo previous steps to keep data consistent after a failure.

Which coordination style uses a central controller in the Saga pattern?

A Orchestration

B Two-phase commit

C Event sourcing

D Choreography

Orchestration uses a central coordinator to manage saga steps.

Why is the Saga pattern better than two-phase commit for microservices?

A It locks resources longer

B It is synchronous

C It improves scalability and uses asynchronous communication

D It requires a central database

Saga pattern avoids long locks and fits asynchronous microservices better.

In the Saga pattern, what triggers the next step in choreography style?

A A central coordinator

B An event published by the previous step

C A timeout event

D Manual intervention

Each service listens for events from previous steps to continue the saga.

What is the main goal of the Saga pattern?

A To centralize all business logic

B To lock all resources during a transaction

C To speed up database queries

D To maintain data consistency across services without distributed locks

Saga ensures data consistency in distributed systems without locking resources.

Explain how the Saga pattern manages distributed transactions and handles failures.

Think about how each step is independent and how the system recovers if something goes wrong.

Compare choreography and orchestration styles in the Saga pattern.

Consider who controls the flow of the saga in each style.