ArangoDB employs various conflict resolution strategies to handle conflicts that may arise in distributed transactions, ensuring data consistency and integrity across multiple database nodes in a distributed environment. Here's how ArangoDB handles conflicts in distributed transactions:
Timestamp-based Conflict Resolution :
* ArangoDB uses timestamps to order and sequence transactions, ensuring that conflicting transactions are resolved based on their temporal order.
* When conflicting transactions occur, ArangoDB compares the timestamps of the conflicting operations and resolves conflicts by favoring the operation with the most recent timestamp.
* By prioritizing the most recent operation, ArangoDB ensures that conflicting changes made by concurrent transactions are applied consistently across all database nodes.
Last-Write-Wins Conflict Resolution :
* In some cases, ArangoDB employs a "last-write-wins" conflict resolution strategy, where the latest write operation supersedes conflicting earlier writes.
* When conflicting writes occur, ArangoDB resolves conflicts by retaining the changes made by the last write operation, discarding conflicting earlier writes.
* This conflict resolution strategy is suitable for scenarios where eventual consistency is acceptable, and the most recent update is considered authoritative.
Custom Conflict Resolution Policies :
* ArangoDB allows developers to define custom conflict resolution policies to handle conflicts based on application-specific criteria and business rules.
* Developers can implement custom conflict resolution logic using user-defined functions (UDFs) or stored procedures to resolve conflicts according to application requirements.
* Custom conflict resolution policies enable developers to implement complex conflict resolution strategies tailored to the specific needs of their applications.
Concurrency Control Mechanisms :
* ArangoDB employs concurrency control mechanisms, such as multi-version concurrency control (MVCC), to manage concurrent access to data and prevent conflicts from occurring.
* MVCC ensures that transactions operate on consistent snapshots of the database, isolating transactions from each other and avoiding interference between concurrent operations.
* By enforcing strict isolation levels and transaction boundaries, ArangoDB minimizes the likelihood of conflicts and maintains data consistency during distributed transactions.
Transaction Rollback and Retry :
* In some cases, ArangoDB may roll back conflicting transactions and retry them to resolve conflicts automatically.
* If a transaction encounters a conflict during execution, ArangoDB may roll back the transaction and retry it after a brief delay, allowing conflicting operations to be resolved before retrying the transaction.
* Transaction rollback and retry mechanisms help ensure that transactions eventually succeed and maintain data consistency across distributed database nodes.
