Node Management

Use commands listed in this section to manage the nodes in your replication cluster.

Creating a Node

To create a node with Spock, connect to the server with psql and use the spock.node_create command:

SELECT spock.node_create(node_name, dsn, location, country, info)

Parameters include:

• a name for the node.
• the dsn of the server on which the node resides.
• connection information for your database.

The location, country, and info are all optional inputs to label nodes and have a default of null.

For example, the following command:

SELECT spock.node_create(n1, ‘host=178.12.15.12 user=carol dbname=accounting’)

Creates a node named n1 that connects to the accounting database on 178.12.15.12, authenticating with the credentials of a user named carol.

Dropping a Node

To drop a node with Spock, connect to the server with psql, and use the spock.node_drop command:

SELECT spock.node_drop(node_name, ifexists)

Parameters include:

• the name of the node.
• ifexists is a boolean value that suppresses an error if the node does not exist when set to true.

For example, the following command:

SELECT spock.node_drop(n1, true)

Drops a node named n1. If the node does not exist, an error message will be suppressed because ifexists is set to true.

Node Management Functions

You can add and remove nodes dynamically with the following SQL functions.

spock.node_create

Use spock.node_create to create a replication node.

spock.node_create(node_name name, dsn text)

Parameters:

• node_name is the name of the new node; only one node is allowed per database.
• dsn is the connection string to the node. For nodes that are supposed to be providers, this should be reachable from the subscription nodes.

spock.node_drop

Use spock.node_drop to drop a replication node.

spock.node_drop(node_name name, ifexists bool)

Parameters:

• node_name is the name of an existing node.
• ifexists specifies the Spock extension behavior with regards to error messages. If true, an error is not thrown when the specified node does not exist. The default is false.

spock.node_add_interface

Use spock.node_add_interface to add an additional interface to a node.

spock.node_add_interface(node_name name, interface_name name, dsn text)

When a node is created, the interface for it is also created using the dsn specified in the create_node command, and with the same name as the node. This interface allows adding alternative interfaces with different connection strings to an existing node.

Parameters:

• node_name is the name of an existing node.
• interface_name is the name of a new interface to be added.
• dsn is the connection string to the node used for the new interface.

spock.node_drop_interface

Use spock.node_drop_interface to remove an existing interface from a node.

spock.node_drop_interface(node_name name, interface_name name)

Parameters:

• node_name is the name of an existing node.
• interface_name is the name of an existing interface.

spock.node_info

Use spock.node_info to return information about the local Spock node.

spock.node_info()

This function queries the Spock catalogs and returns metadata about the current node, including its identifier, name, database information, and any optional descriptive fields that were set during node creation.

This is a read-only query function that does not modify data.