如何找到导致“等待表元数据锁定"的事务?状态?

2021-11-20 00:00:00 mysql

我正在尝试对表执行一些 DDL，并且 SHOW PROCESSLIST 导致等待表元数据锁定"消息.

I am trying to perform some DDL on a table and SHOW PROCESSLIST results in a " Waiting for table metadata lock " message.

我如何知道哪些交易尚未完成?

How can I find out which transaction is not yet closed?

我使用的是 MySQL v5.5.24.

I'm using MySQL v5.5.24.

推荐答案

适用于 MySql 版本 <5.7.3

SHOW ENGINE INNODB STATUS \G

寻找部分-

TRANSACTIONS

我们可以使用INFORMATION_SCHEMA表格.

We can use INFORMATION_SCHEMA Tables.

有用的查询

要检查所有的锁事务正在等待:

To check about all the locks transactions are waiting for:

USE INFORMATION_SCHEMA;
SELECT * FROM INNODB_LOCK_WAITS;

阻止交易的列表:

SELECT * 
FROM INNODB_LOCKS 
WHERE LOCK_TRX_ID IN (SELECT BLOCKING_TRX_ID FROM INNODB_LOCK_WAITS);

或

SELECT INNODB_LOCKS.* 
FROM INNODB_LOCKS
JOIN INNODB_LOCK_WAITS
  ON (INNODB_LOCKS.LOCK_TRX_ID = INNODB_LOCK_WAITS.BLOCKING_TRX_ID);

特定表上的锁列表:

A List of locks on particular table: 

SELECT * FROM INNODB_LOCKS 
WHERE LOCK_TABLE = db_name.table_name;

等待锁定的事务列表:

A list of transactions waiting for locks: 

SELECT TRX_ID, TRX_REQUESTED_LOCK_ID, TRX_MYSQL_THREAD_ID, TRX_QUERY
FROM INNODB_TRX
WHERE TRX_STATE = 'LOCK WAIT';

参考 - MySQL 故障排除:当查询不起作用时该怎么办，第 6 章 - 第 96 页.

Reference - MySQL Troubleshooting: What To Do When Queries Don't Work, Chapter 6 - Page 96.

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