ALTER NODE

Description

Modifies the definition of an existing node.

Precautions

ALTER NODE is an API of the cluster management tool and is used to manage clusters. Only administrators have the permission to use this API. You are advised not to use this API, because doing so affects the cluster.

Syntax

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ALTER NODE nodename WITH
  (
    [ TYPE = nodetype,]
    [ HOST = hostname,]
    [ PORT = portnum,]
    [ HOST1 = 'hostname',]
    [ PORT1 = portnum,]
    [ HOSTPRIMARY [ = boolean ],]
    [ PRIMARY [ = boolean ],]
    [ PREFERRED [ = boolean ],]
    [ SCTP_PORT = portnum,]
    [ CONTROL_PORT = portnum,]
    [ SCTP_PORT1 = portnum,]
    [ CONTROL_PORT1 = portnum, ]
    [ NODEIS_CENTRAL [ = boolean ]]
  );

The port whose number is specified by PORT is used for internal communications between nodes. Unlike the port connecting to an external client, it can be queried in the pgxc_node table.

Parameters

See Parameters in "CREATE NODE."

Examples

-- Create cluster nodes on all CNs.
gaussdb=# CREATE NODE datanode1 WITH(
   TYPE = datanode,
   PREFERRED = false
);

-- Query the initial cluster DN status.
gaussdb=# SELECT node_name, nodeis_preferred FROM pgxc_node WHERE node_type = 'D' ORDER BY 1;
 node_name | nodeis_preferred
-----------+------------------
 datanode1 | f
 datanode2 | f
(2 rows)

-- Set datanode1 as the preferred DN.
gaussdb=# ALTER NODE datanode1 WITH(preferred = true);

-- Query the cluster DN status after the change.
gaussdb=# SELECT node_name, nodeis_preferred FROM pgxc_node WHERE node_type = 'D' ORDER BY 1;
 node_name | nodeis_preferred
-----------+------------------
 datanode1 | t
 datanode2 | f
(2 rows)

-- Connect to only one CN to delete cluster nodes.
gaussdb=# DROP NODE datanode1;

Helpful Links

CREATE NODE and DROP NODE