DEMOTE_SUBCLUSTER_TO_SECONDARY

Converts a to a .

Eon Mode only

Converts a primary subcluster to a secondary subcluster.

Vertica will not allow you to demote a primary subcluster if any of the following are true:

The subcluster contains a critical node.
The subcluster is the only primary subcluster in the database. You must have at least one primary subcluster.
The initiator node is a member of the subcluster you are trying to demote. You must call DEMOTE_SUBCLUSTER_TO_SECONDARY from another subcluster.

Important

This function call can take a long time to complete because all the nodes in the subcluster you are promoting or demoting take a global catalog lock, write a checkpoint, and then commit. This global catalog lock can cause other database tasks to fail with errors.

Schedule calls to this function when other database activity is low.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Volatile

Syntax

DEMOTE_SUBCLUSTER_TO_SECONDARY('subcluster-name')

Parameters

subcluster-name: The name of the primary subcluster to demote to a secondary subcluster.

Privileges

Superuser

Examples

The following example demotes the subcluster analytics_cluster to a secondary subcluster:

=> SELECT DISTINCT subcluster_name, is_primary from subclusters;
  subcluster_name  | is_primary
-------------------+------------
 analytics_cluster | t
 load_subcluster   | t
(2 rows)

=> SELECT DEMOTE_SUBCLUSTER_TO_SECONDARY('analytics_cluster');
 DEMOTE_SUBCLUSTER_TO_SECONDARY
--------------------------------
 DEMOTE SUBCLUSTER TO SECONDARY
(1 row)

=> SELECT DISTINCT subcluster_name, is_primary from subclusters;
  subcluster_name  | is_primary
-------------------+------------
 analytics_cluster | f
 load_subcluster   | t
(2 rows)

Attempting to demote the subcluster that contains the initiator node results in an error:

=> SELECT node_name FROM sessions WHERE user_name = 'dbadmin'
   AND client_type = 'vsql';
      node_name
----------------------
 v_verticadb_node0004
(1 row)

=> SELECT node_name, is_primary FROM subclusters WHERE subcluster_name = 'analytics';
      node_name       | is_primary
----------------------+------------
 v_verticadb_node0004 | t
 v_verticadb_node0005 | t
 v_verticadb_node0006 | t
(3 rows)

=> SELECT DEMOTE_SUBCLUSTER_TO_SECONDARY('analytics');
ERROR 9204:  Cannot promote or demote subcluster including the initiator node
HINT:  Run this command on another subcluster