MODIFY BACKEND

Description

This statement is used to modify the attributes of BE nodes. After modifying the attributes of BE nodes, it will affect the query, write, and data distribution of the current node. The following are the attributes that can be modified:

属性	影响
tag.location	The resource tag of the BE, with the default value being default. After modification, it will affect the data balancing of BEs within the same tag group and the BE nodes for data distribution during table creation. For more information, please refer toResource Group
disable_query	Whether to disable queries, with the default value being false. After setting it to true, no new query requests will be scheduled to this BE node.
disable_load	Whether to disable load, with the default value being false. After setting it to true, no new import requests will be scheduled to this BE node.

tip

This command is not supported in the decoupling storage and computing mode.

Syntax

ALTER SYSTEM MODIFY BACKEND <be_identifier> [, <be_identifier> ... ]
SET (
     "<key>" = "<value>"
)

Where:

be_identifier
  : "<be_host>:<be_heartbeat_port>"
  | "<backend_id>"

Required Parameters

1. <be_host>

It can be the hostname or IP address of the BE node.

2. <heartbeat_port>

The heartbeat port of the BE node, the default is 9050.

3. <backend_id>

The ID of the BE node.

tip

<be_host>, <be_heartbeat_port>, and <backend_id> can all be obtained by querying with the SHOW BACKENDS statement.

Access Control Requirements

The user who executes this SQL must have at least the following permissions:

Privilege	Object	Notes
NODE_PRIV

Usage Notes

Since this operation is at the entire BE level and has a wide impact, it may affect the normal querying, loading, and even table creation operations of the entire cluster if not performed carefully. Please operate with caution.

Examples

1. Modify the resource tag of the BE

ALTER SYSTEM MODIFY BACKEND "127.0.0.1:9050" SET ("tag.location" = "group_a");

2. Modify the disable_query attribute of the BE

ALTER SYSTEM MODIFY BACKEND "10002" SET ("disable_query" = "true");

3. Modify the disable_load attribute of the BE

ALTER SYSTEM MODIFY BACKEND "127.0.0.1:9050" SET ("disable_load" = "true");