Introduction In distributed systems and modern databases, maintaining data consistency is critical. This post introduces the concept of transactions, explains ACID properties, and dives into the Two-Phase Commit (2PC) protocol to ensure reliable distributed transactions.
What is a Transaction? A transaction is a sequence of operations performed as a single unit of work. Transactions are designed to be atomic, consistent, isolated, and durable (ACID):
Atomic: All operations succeed or none. Consistent: Database moves from one valid state to another. Isolated: Concurrent transactions don’t interfere. Durable: Changes are permanent once committed. Challenges in Distributed Systems Multiple databases or nodes can be involved. Partial failures can leave the system in an inconsistent state. Simple commit/rollback is not enough when operations span multiple systems. Two-Phase Commit (2PC) The Two-Phase Commit protocol solves these problems by coordinating distributed transactions in two phases:
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