Question

我有一个项目，我在其中插入很多信息到每秒自动增量主键的表，并使用多线程执行此操作，这意味着有许多线程尝试向该表插入新行。因为表上有一个用于插入查询的锁，我不能同时执行插入，因此我无法从线程获得最大性能......

有没有办法克服这种锁定？

Answer 1

您可以在my.cnf中将 innodb_autoinc_lock_mode 设置为1。然后没有用于Auto_increment的LOCK。如果一个Thead回滚看样本

，则可能在值中有漏洞

MariaDB [test]> show variables like 'innodb_autoinc_lock_mode';
+--------------------------+-------+
| Variable_name            | Value |
+--------------------------+-------+
| innodb_autoinc_lock_mode | 1     |
+--------------------------+-------+
1 row in set (0.00 sec)

样本1

MariaDB [test]> start transaction;
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> insert into autoinc VALUES(NULL,'hello');
Query OK, 1 row affected (0.01 sec)



thread 2 ------------------>    MariaDB [test]> start transaction;
thread 2 ------------------>    Query OK, 0 rows affected (0.00 sec)

thread 2 ------------------>    MariaDB [test]> insert into autoinc VALUES(NULL,'world');
thread 2 ------------------>    Query OK, 1 row affected (0.00 sec)

thread 2 ------------------>    MariaDB [test]> commit;
thread 2 ------------------>    Query OK, 0 rows affected (0.00 sec)

thread 2 ------------------>    MariaDB [test]>


MariaDB [test]> commit;
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> select * from autoinc;
+----+-------+
| id | d     |
+----+-------+
|  1 | hello |
|  2 | world |
+----+-------+
2 rows in set (0.00 sec)

MariaDB [test]>

带回滚的示例2

MariaDB [test]> start transaction;
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> insert into autoinc VALUES(NULL,'Guten');
Query OK, 1 row affected (0.00 sec)

thread 2 ------------------>    MariaDB [test]> start transaction;
thread 2 ------------------>    Query OK, 0 rows affected (0.00 sec)

thread 2 ------------------>    MariaDB [test]> insert into autoinc VALUES(NULL,'Tag');
thread 2 ------------------>    Query OK, 1 row affected (0.00 sec)

thread 2 ------------------>    MariaDB [test]> commit;
thread 2 ------------------>    Query OK, 0 rows affected (0.01 sec)

MariaDB [test]> rollback;
Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> select * from autoinc;
+----+-------+
| id | d     |
+----+-------+
|  1 | hello |
|  2 | world |
|  4 | Tag   |
+----+-------+
3 rows in set (0.00 sec)

MariaDB [test]>

MySql innoDB自动增量锁解决方法

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