OrientDB provides support for distributed transactions, allowing transactions to span multiple nodes in a distributed database cluster. Distributed transactions in OrientDB ensure data consistency, atomicity, and isolation across nodes, even in a distributed environment.
* Coordinator-Participant Architecture : In a distributed transaction, OrientDB follows a coordinator-participant architecture. The coordinator node initiates and coordinates the distributed transaction, while the participant nodes execute transactional operations on their respective local datasets.
* Two-Phase Commit Protocol (2PC) : OrientDB uses the Two-Phase Commit Protocol (2PC) to ensure atomicity and consistency of distributed transactions. The 2PC protocol consists of two phases: prepare phase and commit phase.
* Prepare Phase : During the prepare phase, the coordinator node sends a prepare request to all participant nodes, asking them to prepare to commit the transaction. Each participant node verifies whether it can commit the transaction locally without violating any constraints or integrity rules. If all participant nodes successfully prepare to commit, they respond with an acknowledgment to the coordinator.
* Commit Phase : If all participant nodes are prepared to commit, the coordinator sends a commit request to all participant nodes. Upon receiving the commit request, each participant node executes the commit operation locally, making the transaction's changes permanent. Once all participant nodes have committed the transaction, they send an acknowledgment back to the coordinator.
* Transaction Rollback : If any participant node fails to prepare for or commit the transaction during the prepare or commit phase, the coordinator initiates a rollback operation. The coordinator sends a rollback request to all participant nodes, instructing them to abort the transaction and discard any changes made. This ensures that the transaction is rolled back across all nodes, maintaining data consistency and integrity.
* Ensuring Isolation and Consistency : OrientDB maintains isolation and consistency of distributed transactions by ensuring that transactions execute serializably across nodes. While each participant node executes transactional operations independently, OrientDB enforces strict isolation levels to prevent interference or dependency between concurrent transactions. This ensures that transactions maintain the database's consistency and integrity, even in a distributed environment.
* Handling Failures and Recovery : OrientDB handles failures and recovery in distributed transactions by employing mechanisms such as transaction logs, checkpointing, and recovery protocols. In the event of node failures or network partitions, OrientDB can recover from incomplete transactions and restore the database to a consistent state using transaction logs and recovery procedures.
