This topic introduces the cluster of MDEX Engine nodes and describes its capabilities.
About the cluster
A cluster is composed of a set of MDEX Engine nodes. All nodes can serve query requests. Only one node is identified as the leader node; All other nodes are follower nodes. All of the MDEX Engine nodes share and use one copy of the on-disk representation of the MDEX Engine index.
The Cluster Coordinator provides communication between the nodes in the cluster. The Cluster Coordinator is also used to notify the follower nodes about index updates and updates to the configuration.
Cluster capabilities
A cluster of MDEX Engine nodes provides the following capabilities:
In a cluster, you can perform the following administrative tasks:
- Enhanced availability of query processing by the MDEX Engine. In a cluster, if one of the nodes fails, queries continue to be processed by other nodes in the cluster.
- Increased throughput by the MDEX Engine. In a cluster, you change throughput capacity by adding or removing nodes. By adding nodes you can spread the query load across multiple MDEX Engine instances without the need to increase storage requirements at the same rate. You can add or remove nodes dynamically, without having to stop the cluster.
- Add one or more MDEX Engine instances to a cluster.
- Remove MDEX Engine instances while allowing the cluster to continue running.
- Identify a single node to which you can send data during an initial index data load and subsequent updates. (The administration and configuration updates must also be sent to this node.) All types of updates are automatically propagated to all MDEX Engine nodes while one or more MDEX Engine nodes continue to process queries.
