MySQL Bugs: #72902: auto increment value for table not affected by update statement

Bug #72902	auto increment value for table not affected by update statement
Submitted:	6 Jun 2014 17:46	Modified:	6 Jun 2014 20:58
Reporter:	Trey Raymond	Email Updates:
Status:	Not a Bug	Impact on me:	None
Category:	MySQL Server	Severity:	S3 (Non-critical)
Version:	5.5.34	OS:	Linux
Assigned to:		CPU Architecture:	Any

Description:
see the how to repeat.  when updating the auto increment value to one higher than the max in the table before, the table should set its autoinc to that value +1 (AUTO_INCREMENT=2), but it does not - it waits for an insert statement to do so.  this causes the same insert statement executed twice in a row to fail once, succeed the second time.

How to repeat:
mysql> CREATE TABLE `test` (
    ->   `id` int(10) unsigned NOT NULL,
    ->   `a` varchar(10) NOT NULL,
    ->   PRIMARY KEY (`id`),
    ->   UNIQUE KEY `a` (`a`)
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.01 sec)

mysql> insert into test (a) values ('hello');
Query OK, 1 row affected, 1 warning (0.00 sec)

mysql> select * from test;
+----+-------+
| id | a     |
+----+-------+
|  0 | hello |
+----+-------+
1 row in set (0.01 sec)

mysql> alter table test modify id int(10) unsigned NOT NULL auto_increment;
Query OK, 1 row affected (0.02 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> select * from test;
+----+-------+
| id | a     |
+----+-------+
|  0 | hello |
+----+-------+
1 row in set (0.00 sec)

mysql> update test set id=1 where a='hello';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from test;
+----+-------+
| id | a     |
+----+-------+
|  1 | hello |
+----+-------+
1 row in set (0.00 sec)

mysql> show create table test\G
*************************** 1. row ***************************
       Table: test
Create Table: CREATE TABLE `test` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `a` varchar(10) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `a` (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> insert into test (a) values ('world');
ERROR 1062 (23000): Duplicate entry '1' for key 'PRIMARY'
mysql> select * from test;
+----+-------+
| id | a     |
+----+-------+
|  1 | hello |
+----+-------+
1 row in set (0.00 sec)

mysql> show create table test\G
*************************** 1. row ***************************
       Table: test
Create Table: CREATE TABLE `test` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `a` varchar(10) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `a` (`a`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> insert into test (a) values ('world');
Query OK, 1 row affected (0.00 sec)

mysql> select * from test;
+----+-------+
| id | a     |
+----+-------+
|  1 | hello |
|  2 | world |
+----+-------+
2 rows in set (0.00 sec)

mysql> show create table test\G
*************************** 1. row ***************************
       Table: test
Create Table: CREATE TABLE `test` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `a` varchar(10) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `a` (`a`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

Suggested fix:
ensure that an update which increases the max value of an auto increment column affects the tables stored auto-inc value.  may be complex due to innodb autoinc lock modes.

Thank you for the bug report. Not repeatable with latest release 5.5.38. Please
upgrade.

c:\mysql-5.5.38-winx64>bin\mysql -uroot test
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.5.38 MySQL Community Server (GPL)

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Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> CREATE TABLE `test` (`id` int(10) unsigned NOT NULL, `a` varchar(10) NOT NULL,PRIMARY KEY (`id`),UNIQUE KEY `a` (`a`))
    -> ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected (0.11 sec)

mysql> insert into test (a) values ('hello');
Query OK, 1 row affected, 1 warning (0.03 sec)

mysql> alter table test modify id int(10) unsigned NOT NULL auto_increment;
Query OK, 1 row affected (0.25 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> select * from test;
+----+-------+
| id | a     |
+----+-------+
|  1 | hello |
+----+-------+
1 row in set (0.00 sec)