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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
var addDatabaseNodeOp = new AddDatabaseNodeOperation("Northwind");

// Execute the operation by passing it to Maintenance.Server.Send
DatabasePutResult result = store.Maintenance.Server.Send(addDatabaseNodeOp);

// Can access the new topology
var numberOfReplicas = result.Topology.AllNodes.Count();
    // Create the AddDatabaseNodeOperation
// Add a random node to 'Northwind' database-group
var addDatabaseNodeOp = new AddDatabaseNodeOperation("Northwind");

// Execute the operation by passing it to Maintenance.Server.SendAsync
DatabasePutResult result = await store.Maintenance.Server.SendAsync(addDatabaseNodeOp);

// Can access the new topology
var numberOfReplicas = result.Topology.AllNodes.Count();

    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
var addDatabaseNodeOp = new AddDatabaseNodeOperation("Northwind", "C");

// Execute the operation by passing it to Maintenance.Server.Send
DatabasePutResult result = store.Maintenance.Server.Send(addDatabaseNodeOp);
    // Create the AddDatabaseNodeOperation
// Add node C to 'Northwind' database-group
var addDatabaseNodeOp = new AddDatabaseNodeOperation("Northwind", "C");

// Execute the operation by passing it to Maintenance.Server.SendAsync
DatabasePutResult result = await store.Maintenance.Server.SendAsync(addDatabaseNodeOp);

    Syntax 

    public AddDatabaseNodeOperation(string databaseName, string nodeTag = null)
    Parameters Type Description
    databaseName string Name of a database for which to add the node.
    nodeTag string Tag of node to add.
    Default: a random node from the existing cluster topology will be added.
    Object returned by Send operation:
    DatabasePutResult    		 Type Description
    RaftCommandIndex long Index of the raft command that was executed
    Name string Database name
    Topology DatabaseTopology The database topology
    NodesAddedTo List<string> New nodes added to the cluster topology.
    Will be 0 for this operation.

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