Removing nodes from a database

In an Eon Mode database, you remove nodes from the subcluster that contains them, rather than from the database.

Note

In an Eon Mode database, you remove nodes from the subcluster that contains them, rather than from the database. See Removing Nodes for more information.

As long as there are enough nodes remaining to satisfy the K-Safety requirements, you can remove the node from a database. You cannot drop nodes that are critical for K-safety. See Lowering K-Safety to enable node removal.

You can remove nodes from a database using one of the following:

Management Console interface
Administration Tools

Prerequisites
Before removing a node from the database, verify that the database complies with the following requirements:

It is running.
It has been backed up.
The database has the minimum number of nodes required to comply with K-safety. If necessary, temporarily lower the database K-safety level.
All of the nodes in your database must be either up or in active standby. Vertica reports the error "All nodes must be UP or STANDBY before dropping a node" if you attempt to remove a node while a database node is down. You will get this error, even if you are trying to remove the node that is down.

Management Console

Remove nodes with Management Console from its Manage page:

Remove database nodes as follows:

Choose the node to remove.
Click Remove node in the Node List.

The following restrictions apply:

You can only remove nodes that belong to the database cluster.
You cannot remove DOWN nodes.

When you remove a node, its state changes to STANDBY. You can later add STANDBY nodes back to the database.

Administration tools

To remove unused hosts from the database using Administration Tools:

Open the Administration Tools. See Using the administration tools for information about accessing the Administration Tools.
On the Main Menu, select View Database Cluster State to verify that the database is running. If the database is not running, start it.
From the Main Menu, choose Advanced Menu and choose OK.
In the Advanced menu, choose Cluster Management and choose OK.
In the Cluster Management menu, choose Remove Host(s) from Database and choose OK.
When warned that you must redesign your database and create projections that exclude the hosts you are going to drop, choose Yes.
Select the database from which you want to remove the hosts and choose OK.

A list of currently active hosts appears.
Select the hosts you want to remove from the database and choose OK.
When prompted, choose OK to confirm that you want to remove the hosts.
When informed that the hosts were successfully removed, choose OK.
If you removed a host from a Large Cluster configuration, open a vsql session and run realign_control_nodes:
```
SELECT realign_control_nodes();
```
For more details, see REALIGN_CONTROL_NODES.
If this host is not used by any other database in the cluster, you can remove the host from the cluster. See Removing hosts from a cluster.