Saga Design Pattern
In this article, I will discuss the Saga design pattern. First, we'll address some technical challenges of creating ACID transactions. Then, we'll explore the Saga design pattern and how to implement it.
Database Per Service Pattern
First, let's talk about microservice architecture and the database per service pattern. Basically, each microservice in an application has its own dedicated database. This allows each microservice to manage its data independently, making it easier to develop, deploy, and scale each service without affecting the others. For instance, in an online store, the user service, order service, and inventory service each have their own databases. This isolation improves flexibility, as each service can choose the best database type for its needs and makes the system more resilient to failures.
However, there are some drawbacks to this pattern. Data consistency and distributed transactions are two of them. Since each microservice operates independently, it can lead to potential inconsistencies when updates occur across multiple services. Data duplication across the system can also lead to synchronization issues. Each transaction needs to be distributed across the system. If a failure occurs, rollbacks must happen across the system, leading to another problem: distributed transactions.
What is the Saga Design Pattern?
The Saga design pattern is a method for managing long-running transactions in a microservice architecture by breaking down a complex transaction into a series of smaller, independent steps, each handled by a different service. If any step fails, compensating transactions are executed to undo the changes made by previous steps, ensuring data consistency across all services. This pattern can be implemented through choreography, where each service triggers the next step via events, or orchestration, where a central coordinator directs each step. First let’s talk about Choreography.