Replication in ArangoDB is a feature that enables the synchronization of data across multiple database instances, ensuring data availability, fault tolerance, and scalability. ArangoDB's replication mechanism allows you to create replicas of databases or collections on one or more servers, providing redundancy and high availability in distributed environments. Here's how replication works in ArangoDB:
Replication Setup :
* In ArangoDB, replication is typically configured using a master-slave replication model, where one server (the master) serves as the primary source of data, and one or more servers (the slaves) replicate data from the master.
* To set up replication, you configure replication endpoints on both the master and slave servers, specifying the addresses of the servers and authentication credentials (if required).
Replication Process :
* The replication process in ArangoDB involves the following steps:
* Replication Logs: The master server generates replication logs (also known as "oplogs" or "write-ahead logs") that record changes to the database, including inserts, updates, and deletes.
* Replication Requests: The slave servers periodically poll the master server for replication logs and request updates to synchronize their data.
* Data Transfer: The master server streams replication logs to the slave servers over the network, transmitting the changes made to the database.
* Data Application: The slave servers apply the replication logs received from the master, replaying the changes to their local databases to mirror the state of the master database.
* Acknowledgment: Once the replication logs are successfully applied, the slave servers acknowledge receipt to the master, confirming that the data has been replicated.
Replication Topologies :
* ArangoDB supports various replication topologies, including:
* Master-Slave Replication: One master server replicates data to one or more slave servers.
* Master-Master Replication: Multiple master servers replicate data bidirectionally to each other, allowing for active-active replication and distributed writes.
* Replica Sets: A group of servers forms a replica set, with one primary server and one or more secondary servers. If the primary server fails, one of the secondary servers is elected as the new primary.
Conflict Resolution :
* In master-master replication scenarios, conflicts may arise when multiple servers concurrently modify the same data.
* ArangoDB provides conflict resolution mechanisms to handle conflicts and ensure data consistency, such as last-write-wins, timestamp-based conflict resolution, or custom conflict resolution policies.
Monitoring and Management :
* ArangoDB provides monitoring tools and management interfaces to monitor replication status, track replication lag, and manage replication settings.
* Administrators can configure replication settings, monitor replication performance, and troubleshoot replication issues using built-in monitoring and management tools.
