Saga Pattern, Outbox and Idempotency: Keeping Consistency in Distributed Systems

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As software architectures shift from monolithic relational databases to microservices, NoSQL stores, and event queues, traditional ACID transactions are no longer sufficient for ensuring data consistency. The Saga Pattern addresses this by breaking large operations into smaller local transactions, each paired with a compensating action to reverse changes if a later step fails. Two orchestration approaches exist: choreography, where services react independently to events with low coupling but implicit flow, and orchestration, where a central coordinator manages each step with greater visibility but tighter coupling. Supporting patterns such as the Transactional Outbox prevent message loss, while idempotency ensures repeated operations do not cause unintended side effects. Together, these techniques allow distributed systems to achieve eventual consistency without relying on a single coordinating database.

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