ALTER NODE nodename WITH
[ TYPE = nodetype,]
[ HOST = hostname,]
[ PORT = portnum,]
[ PRIMARY [ = boolean],]
[ PREFERRED [ = boolean ] ]
The following description applies only to Postgres-XC
ALTER NODE is new SQL query specific to Postgres-XC since 0.9.7 that modifies cluster node information in catalog pgxc_node.
Node connection that has been modified does not guaranty that connection information cached in pooler is updated accordingly.
ALTER NODE only runs on the local node where it is launched.
- The name of the selected cluster node.
- The type of the cluster node. It is possible to specify a Coordinator node or a Datanode node.
- Defines if the cluster node is used as a primary node for replicated write operations. A boolean value can be specified. In case no value is specified, PRIMARY acts like true.
- Defines if the cluster node is used as a preferred node for replicated read operations. A boolean value can be specified. In case no value is specified, PREFERRED acts like true.
- The node type for given cluster node. Possible values are: 'coordinator' for a Coordinator node and 'datanode' for a Datanode node.
- The hostname or IP used to connect to the cluster node.
- The port number used to connect to the cluster node.
A Datanode can be modified as PRIMARY and as PREFERRED as many times as necessary.
A node type cannot be modified.
Modify a Coordinator node located on local machine to use port 6543.
ALTER NODE coord_node WITH (PORT = 6543, HOST = 'localhost');
ALTER NODE does not conform to the SQL standards, it is a Postgres-XC specific command.