The ArangoDB Agency is a component of ArangoDB's architecture that serves as a coordination and management layer for distributed deployments. It is responsible for managing and coordinating various aspects of the distributed database, such as cluster membership, leader election, configuration synchronization, failover handling, and distributed transactions.
Here are some key features and responsibilities of the ArangoDB Agency :
Cluster Membership Management :
* The Agency keeps track of the nodes (servers) that are part of the ArangoDB cluster, including their status, availability, and roles.
* It maintains a consistent view of the cluster membership across all nodes and ensures that the cluster remains stable and operational.
Leader Election :
* In distributed environments, the Agency is responsible for electing a leader node to coordinate cluster-wide operations, such as data distribution, query routing, and transaction management.
* The leader node is responsible for making decisions and coordinating actions across the cluster, ensuring consistency and fault tolerance.
Configuration Synchronization :
* The Agency ensures that configuration settings and metadata are synchronized across all nodes in the cluster.
* It propagates changes to configuration parameters, such as replication factor, shard placement, and index settings, to ensure consistency and coherence in the distributed database environment.
Failover Handling :
* In the event of node failures or network partitions, the Agency coordinates failover handling and recovery procedures to maintain data availability and consistency.
* It triggers automatic failover mechanisms to promote replica nodes to leadership roles and redistribute data as needed to ensure uninterrupted operation.
Distributed Transactions :
* The Agency facilitates distributed transactions across multiple nodes in the cluster, ensuring ACID (Atomicity, Consistency, Isolation, Durability) properties and data integrity.
* It coordinates transactional operations, such as commit and rollback, across participating nodes to ensure that all changes are applied atomically and consistently.
