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    Adding a Database Node

    • When creating a database, you can specify the number of replicas for that database.
      This determines the number of database instances in the database-group.

    • The number of replicas can be dynamically increased even after the database is up and running,
      by adding more nodes to the database-group.

    • The nodes added must already exist in the cluster topology.

    • Once a new node is added to the database-group,
      the cluster assigns a mentor node (from the existing database-group nodes) to update the new node.

    • In this page:

    Add database node - random

    • Use AddDatabaseNodeOperation to add another database-instance to the database-group.
    • The node added will be a random node from the existing cluster nodes. 

    // Create the AddDatabaseNodeOperation
// Add a random node to 'Northwind' database-group
const addDatabaseNodeOp = new AddDatabaseNodeOperation("Northwind");

// Execute the operation by passing it to maintenance.server.send
const result = await documentStore.maintenance.server.send(addDatabaseNodeOp);

// Can access the new topology
const numberOfReplicas = getAllNodesFromTopology(result.topology).length;

    Add database node - specific

    • You can specify the node tag to add.
    • This node must already exist in the cluster topology.

    // Create the AddDatabaseNodeOperation
// Add node C to 'Northwind' database-group
const addDatabaseNodeOp = new AddDatabaseNodeOperation("Northwind", "C"));

// Execute the operation by passing it to maintenance.server.send
const result = await documentStore.maintenance.server.send(addDatabaseNodeOp);

    Syntax 

    const addDatabaseNodeOp = new AddDatabaseNodeOperation(databaseName, nodeTag?);
    Parameters Type Description
    databaseName string Name of a database for which to add the node.
    nodeTag string Tag of node to add.
    Default: If not passed then a random node from the existing cluster topology will be added.
    Object returned by send operation has: Type Description
    raftCommandIndex number Index of the raft command that was executed
    name string Database name
    topology DatabaseTopology The database topology
    nodesAddedTo string[] New nodes added to the cluster topology.
    Will be 0 for this operation.

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