KILL-PolarDB(PolarDB)-阿里云帮助中心

Use the KILL statement to stop a running SQL thread on a PolarDB for Xscale instance.

Syntax

PolarDB for Xscale supports three forms of the KILL statement:

-- Stop the logical and physical SQL threads of a connection, then close it
KILL PROCESS_ID

-- Stop a specific physical SQL thread
KILL 'PHYSICAL_PROCESS_ID'

-- Stop all physical SQL threads on the instance
KILL 'ALL'

Note PolarDB for Xscale does not support KILL QUERY.

How it works

PolarDB for Xscale is a distributed database. When a query runs, it spawns both a logical SQL thread on the coordinator node and one or more physical SQL threads on the underlying storage nodes. The three KILL forms target different layers:

Form	Scope	Effect
`KILL PROCESS_ID`	Logical + physical	Stops both the logical and physical SQL threads of a connection, then closes the connection
`KILL 'PHYSICAL_PROCESS_ID'`	Physical only	Stops a specific physical SQL thread on a storage node
`KILL 'ALL'`	All physical	Stops all physical SQL threads on the instance

Kill a connection

To stop a connection and all its associated SQL threads:

Get the PROCESS_ID of the target connection:
```
SHOW [FULL] PROCESSLIST;
```
Kill the connection:
```
KILL PROCESS_ID;
```
Replace PROCESS_ID with the numeric ID from SHOW [FULL] PROCESSLIST.

Kill a physical SQL thread

To stop a specific physical SQL thread on a storage node:

Get the PHYSICAL_PROCESS_ID of the target thread:
```
SHOW PHYSICAL_PROCESS_ID;
```
Kill the physical thread:
```
KILL 'PHYSICAL_PROCESS_ID';
```
Replace PHYSICAL_PROCESS_ID with the string value from step 1. The value is dash-separated (for example, 0-0-521570) and must be enclosed in double quotation marks (").
Example:
```
KILL '0-0-521570';
```
```
Query OK, 0 rows affected (0.01 sec)
```

Kill all physical SQL threads

To stop all physical SQL threads running on the instance:

KILL 'ALL';

Limitations

KILL QUERY is not supported. To stop a query, kill the connection with KILL PROCESS_ID.
PHYSICAL_PROCESS_ID is a string value, not a numeric value. Always enclose it in double quotation marks (").