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ALTER NODE GROUP

Updated at: Mar 13, 2020 GMT+08:00

Function

ALTER NODE GROUP modifies the information about a Node Group.

Precautions

  • Only a system administrator is allowed to modify Node Group information.
  • Node Group modification operations (excluding SET DEFAULT) are internal and need to be performed in maintenance mode (by invoking set xc_maintenance_mode=on;).
  • ALTER NODE GROUP can be used only within a database. To avoid data inconsistency in DBMS, do not manually run this SQL statement.

Syntax

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ALTER NODE GROUP groupname
    | SET DEFAULT
    | RENAME TO new_group_name
    | SET VCGROUP RENAME TO new_group_name
    | SET NOT VCGROUP
    | SET TABLE GROUP new_group_name
    | COPY BUCKETS FROM src_group_name
    | ADD NODE ( nodename [, ... ] )
    | DELETE NODE ( nodename [, ... ] )
    | RESIZE TO dest_group_name
    | SET VCGROUP WITH GROUP new_group_name

Parameter Description

  • groupname

    Specifies the Node Group to be renamed.

    Value range: a string compliant with the naming convention rules

  • SET DEFAULT

    Sets in_redistribution to 'y' for all Node Groups excluding the one specified by groupname. To be compatible with earlier versions, this syntax is retained and does not need to be executed in maintenance mode.

  • RENAME TO new_group_name

    Renames the Node Group specified by groupname to new_group_name.

  • SET VCGROUP RENAME TO new_group_name

    Converts the entire physical cluster into a logical cluster. After the conversion, groupname is the logical cluster name, and the original physical cluster is changed to new_group_name.

  • SET NOT VCGROUP

    Converts all logical clusters to common Node Groups and changes group_kind from 'v' to 'n' for all of them.

  • SET TABLE GROUP new_group_name

    Changes all the group_names in the pgroup columns of the pgxc_class tables on all CNs to new_group_name.

  • COPY BUCKETS FROM src_group_name

    Copies values in the group_members and group_bucketcontent columns from the Node Group specified by src_group_name to the Node Group specified by groupname.

  • ADD NODE ( nodename [, ... ] )

    Adds nodes from the Node Group specified by groupname. After the statement execution, the new nodes are registered with the pgxc_node system catalog. This statement only modifies the system catalog and does not add nodes or redistribute data. Do not invoke this statement.

  • DELETE NODE ( nodename [, ... ] )

    Deletes nodes from the Node Group specified by groupname. The deleted nodes still exist in the pgxc_node system catalog. This statement only modifies the system catalog and does not delete nodes or redistribute data. Do not invoke this statement.

  • RESIZE TO dest_group_name

    Specifies a resize flag for the cluster. Set the Node Group specified by groupname to the Node Group before data redistribution and set is_installation of the Node Group to FALSE. Set desst_group_name to the Node Group after data redistribution and set is_installation of the Node Group to TRUE.

  • SET VCGROUP WITH GROUP new_group_name

    Converts a physical cluster into a logical cluster. After the conversion, groupname is still the physical cluster, and new_group_name is the name of the logical cluster.

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