A distributed transaction is a type of transaction that involves multiple, distinct data repositories or databases, often spread across different networked systems. Unlike a simple transaction that occurs within a single database, a distributed transaction ensures that a series of operations across multiple databases are completed successfully as a single unit or not at all, thereby maintaining data integrity and consistency.
Key Characteristics of Distributed Transactions
ACID Properties: Distributed transactions adhere to the ACID (Atomicity, Consistency, Isolation, Durability) principles, ensuring that all operations within the transaction are completed successfully or none are, maintaining the integrity of the data across all involved databases[1][2].
Two-Phase Commit (2PC): A common protocol used in distributed transactions is the two-phase commit. This involves a "prepare" phase where all participating nodes agree to commit the transaction, followed by a "commit" phase where the transaction is finalized. If any node fails to prepare, the transaction is rolled back across all nodes[2][4].
Transaction Coordinator: A transaction coordinator manages the distributed transaction, ensuring that all participating nodes either commit or roll back the transaction. The coordinator handles communication between nodes and ensures that the transaction's outcome is consistent across all databases[1][2].
Failure Handling: Distributed transactions must handle various types of failures, such as network issues or node crashes. Mechanisms are in place to detect failures and either retry the transaction or roll it back to maintain consistency[1][2].
Example Use Cases
Financial Transactions: Transferring money between accounts in different banks requires a distributed transaction to ensure that the debit and credit operations are both completed successfully.
Microservices Architectures: In a microservices architecture, different services may have their own databases. A distributed transaction ensures that operations across these services are consistent, such as updating an order status and inventory count simultaneously[6][7].
Challenges
Complexity: Implementing distributed transactions is more complex than single-database transactions due to the need to coordinate multiple systems and handle potential points of failure[2][12].
