Eventual consistency handling in Microservices - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is eventual consistency in distributed systems?

Eventual consistency means that, over time, all parts of a system will have the same data, but they might be temporarily different right after a change.

beginner

Why is eventual consistency important in microservices?

Because microservices often work independently and communicate asynchronously, eventual consistency helps keep data correct without slowing down the system.

intermediate

Name a common pattern used to handle eventual consistency.

The Saga pattern is often used. It breaks a big transaction into smaller steps with compensations to fix errors later.

intermediate

What role do message queues play in eventual consistency?

Message queues help by storing and delivering updates between services reliably, allowing them to update data asynchronously and eventually become consistent.

advanced

How can conflicts be resolved in an eventually consistent system?

Conflicts can be resolved using techniques like last-write-wins, version vectors, or manual reconciliation depending on the use case.

What does eventual consistency guarantee in a system?

A All data will be the same eventually

B Data is always immediately consistent

C Data is never consistent

D Data consistency depends on user input

Eventual consistency means data will become consistent over time, not immediately.

Which pattern helps manage distributed transactions with eventual consistency?

A Saga pattern

B Singleton pattern

C Factory pattern

D Observer pattern

The Saga pattern breaks transactions into steps with compensations to handle eventual consistency.

What is a common tool to enable asynchronous communication in microservices?

A Synchronous HTTP calls

B Direct database access

C Message queue

D Local file system

Message queues allow services to communicate asynchronously, supporting eventual consistency.

Which technique is NOT typically used to resolve conflicts in eventual consistency?

A Last-write-wins

B Version vectors

C Manual reconciliation

D Immediate locking

Immediate locking is not used in eventual consistency because it blocks updates and reduces availability.

Why might a system choose eventual consistency over strong consistency?

A To simplify database design

B To improve availability and performance

C To avoid using message queues

D To ensure immediate data accuracy

Eventual consistency improves availability and performance by allowing temporary differences in data.

Explain how the Saga pattern helps in handling eventual consistency in microservices.

Think about how a big task can be split into smaller tasks that can be reversed if something goes wrong.

Describe the role of message queues in achieving eventual consistency.

Imagine a post office that holds letters until the receiver is ready.