DROP BACKEND

Description

This statement is used to remove BE nodes from the Doris cluster.

Syntax

ALTER SYSTEM DROP BACKEND "<be_identifier>" [, "<be_identifier>" ... ]

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

1. It is not recommended to use this command to take a BE node offline. This command will directly remove the BE node from the cluster. The data on the current node will not be load-balanced to other BE nodes. Data loss may occur if there are single-replica tables in the cluster. A better approach is to use the DECOMMISSION BACKEND command to gracefully take the BE node offline.
2. Since this operation is a high-risk operation, when you directly run this command:

   ALTER SYSTEM DROP BACKEND "127.0.0.1:9050";

   ERROR 1105 (HY000): errCode = 2, detailMessage = It is highly NOT RECOMMENDED to use DROP BACKEND stmt.It is not safe to directly drop a backend. All data on this backend will be discarded permanently. If you insist, use DROPP instead of DROP
   The above prompt message will appear. If you understand what you are doing, you can replace the DROP keyword with DROPP and continue:

   ALTER SYSTEM DROPP BACKEND "127.0.0.1:9050";

Examples

1. Remove two nodes from the cluster based on the Host and HeartbeatPort of the BE nodes:

   ALTER SYSTEM DROPP BACKEND "192.168.0.1:9050", "192.168.0.2:9050";

2. Remove one node from the cluster based on the ID of the BE node:

   ALTER SYSTEM DROPP BACKEND "10002";