Distributed Transaction Protocols
What are Distributed Transaction Protocols?
Distributed transaction protocols are algorithms that ensure ACID properties (Atomicity, Consistency, Isolation, Durability) across multiple distributed systems. They coordinate transactions that span multiple databases, services, or nodes to maintain data consistency.
Problem they Solve
When a transaction involves multiple distributed systems, ensuring that either all operations succeed or all fail becomes complex. These protocols solve the challenge of maintaining data consistency across distributed systems in the presence of network failures, node crashes, and other distributed system challenges.
Common Protocols
Two-Phase Commit (2PC)
A coordinator asks all participants to prepare, then commits if all agree. Simple but has blocking issues if coordinator fails.
Three-Phase Commit (3PC)
Adds a pre-commit phase to 2PC to reduce blocking, but still vulnerable to network partitions.
Saga Pattern
Manages transactions through a series of compensating actions, allowing for eventual consistency.
Paxos/Raft
Consensus algorithms that ensure agreement among distributed nodes for transaction ordering.
Common Use Cases
- • Financial Systems: Bank transfers involving multiple accounts
- • E-commerce: Order processing across inventory, payment, and shipping systems
- • Microservices: Coordinating transactions across multiple services
- • Database Sharding: Transactions spanning multiple shards
- • Distributed Databases: Ensuring consistency in systems like CockroachDB
Trade-offs
- • Performance: Adding coordination overhead
- • Availability: May block during coordinator failures
- • Complexity: Increased system complexity and failure modes
- • CAP Theorem: Must choose between consistency and availability during partitions