mysql innodb_locks table 转储到文件

Question

根据 mysql 关于 InnoDB Transaction and Locking Information page 的参考：

The data exposed by the transaction and locking tables (INNODB_TRX, INNODB_LOCKS, and INNODB_LOCK_WAITS) represents a glimpse into fast-changing data.

For performance reasons, and to minimize the chance of misleading joins between the transaction and locking tables, InnoDB collects the required transaction and locking information into an intermediate buffer whenever a SELECT on any of the tables is issued.

所以我想知道是否有办法将这个 info/buffer 写入文件？

Answer 1

我认为没有任何方法可以直接访问您所说的缓冲区。您可以对命名的 INFORMATION_SCHEMA tables 使用 SELECT 查询，它将间接地从这些缓冲区中读取。

另一种方法是每 15 秒将 SHOW ENGINE INNODB STATUS 的输出转储到 MySQL 服务器错误日志中。您可以选择使此状态包含锁定信息。参见 https://dev.mysql.com/doc/refman/5.6/en/innodb-enabling-monitors.html

示例：我启用了带有锁定选项的 InnoDB 锁定监视器。

mysql> set global innodb_status_output_locks=on;
mysql> set global innodb_status_output=on;

然后我创建了一个事务，插入到测试中table。但先不要承诺。

mysql> BEGIN;
mysql> INSERT INTO t VALUES (1,1);

在第二个 window 后，我开始了另一个事务，另一个插入设计为与第一个插入冲突。

mysql> INSERT INTO t VALUES (1,1);

挂起，等待第一个会话持有的锁。

然后跟踪 MySQL 错误日志，观察锁：

------------
TRANSACTIONS
------------
Trx id counter 3528210
Purge done for trx's n:o < 3528208 undo n:o < 0 state: running but idle
History list length 814
LIST OF TRANSACTIONS FOR EACH SESSION:
---TRANSACTION 3528209, ACTIVE 30 sec inserting
mysql tables in use 1, locked 1
LOCK WAIT 2 lock struct(s), heap size 360, 1 row lock(s)
MySQL thread id 1, OS thread handle 0x70000a4bd000, query id 23 localhost root update
insert into t values (1,1,null,null)
------- TRX HAS BEEN WAITING 30 SEC FOR THIS LOCK TO BE GRANTED:
RECORD LOCKS space id 3342 page no 3 n bits 72 index `PRIMARY` of table `test`.`t` trx id 3528209 lock mode S locks rec but not gap waiting
------------------
TABLE LOCK table `test`.`t` trx id 3528209 lock mode IX
RECORD LOCKS space id 3342 page no 3 n bits 72 index `PRIMARY` of table `test`.`t` trx id 3528209 lock mode S locks rec but not gap waiting
---TRANSACTION 3528208, ACTIVE 49 sec
2 lock struct(s), heap size 360, 1 row lock(s), undo log entries 1
MySQL thread id 2, OS thread handle 0x70000a501000, query id 17 localhost root
TABLE LOCK table `test`.`t` trx id 3528208 lock mode IX
RECORD LOCKS space id 3342 page no 3 n bits 72 index `PRIMARY` of table `test`.`t` trx id 3528208 lock_mode X locks rec but not gap

mysql innodb_locks table 转储到文件

mysql innodb_locks table dump to file

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