pingcap/tidb

Can't use pt-kill to kill TiDB connections

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#27,932 opened on Sep 9, 2021

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Description

Bug Report

Can't use pt-kill from percona-toolkit to kill TiDB connections.

Because it uses a kill '1' syntax, but tidb only supports kill 1.

1. Minimal reproduce step (Required)

Run a tidb locally, and run select sleep(50); in a connection. Then run pt-kill --kill --user=root --match-command=Query --host=127.0.0.1 --port=4000 -v.

2. What did you expect to see? (Required)

Successfully kill the sleep(50) connection.

3. What did you see instead (Required)

In pt-kill's output:

Error killing 3: DBD::mysql::st execute failed: You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 8 near "'3'"  [for Statement "KILL ?" with ParamValues: 0=3] at /usr/bin/vendor_perl/pt-kill line 7046.

In tidb's output:

[WARN] [session.go:1330] ["parse SQL failed"] [conn=7] [error="line 1 column 8 near \"'3'\" "] [SQL="KILL '3'"]
[INFO] [conn.go:997] ["command dispatched failed"] [conn=7] [connInfo="id:7, addr:127.0.0.1:44316 status:10, collation:latin1_swedish_ci, user:root"] [command=Query] [status="inTxn:0, autocommit:1"] [sql="KILL '3'"] [txn_mode=OPTIMISTIC] [err="[parser:1064]You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 8 near \"'3'\" "]

4. What is your TiDB version? (Required)

master

Contributor guide

Tech stack
gosqlmysql
Domain
database
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go programmingMySQL SQL parser basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75
Research direction
Investigate the SQL parser in TiDB to allow KILL with quoted connection IDs. Look at the parser files (likely in `parser/` directory) and the session handling in `session.go` and `conn.go`. The fix should modify the grammar or parser to accept both `KILL 'id'` and `KILL id`. Add corresponding tests to ensure compatibility.