Distributed Transactions (2PC, Saga) in System Design

In the complex landscape of modern distributed systems, maintaining data consistency across multiple independent services and databases presents one of the most challenging problems in system design. Distributed transactions provide the foundation for ensuring that operations spanning several resources either succeed completely or fail entirely, preserving the ACID properties of atomicity, consistency, isolation, and durability. This article explores two primary approaches to handling distributed transactions: the Two-Phase Commit protocol, commonly known as 2PC, and the Saga pattern. Each method addresses the coordination of long-running transactions in environments where traditional single-database transactions fall short. What Are Distributed Transactions A distributed transaction involves multiple participating resources, such as separate databases, microservices, or external systems, that must coordinate to achieve a unified outcome. Unlike local transactions confined to a single