database - MySQL 5.5 foreign key constraint fails when foreign key exists

Question

Just installed MySQL 5.5 on mac os x 10.6 and am having a strange issue on many tables. Below is an example. Inserting a row fails with a foreign key constraint when it shouldn't. The foreign key it references does exist. Any ideas?

mysql> show create table Language;
+----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table    | Create Table                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Language | CREATE TABLE `Language` (
  `Id` int(11) NOT NULL AUTO_INCREMENT,
  `Code` varchar(2) NOT NULL,
  `Name` varchar(63) CHARACTER SET utf8 DEFAULT NULL,
  `Variant` varchar(63) CHARACTER SET utf8 DEFAULT NULL,
  `Country_Id` int(11) DEFAULT NULL,
  PRIMARY KEY (`Id`),
  UNIQUE KEY `Code` (`Code`,`Country_Id`,`Variant`),
  KEY `FKA3ACF7789C1796EB` (`Country_Id`),
  CONSTRAINT `FKA3ACF7789C1796EB` FOREIGN KEY (`Country_Id`) REFERENCES `Country` (`Id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1 |
+----------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> show create table Language_Phrases;
+------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table            | Create Table                                                                                                                                                                                                                                                                                                                                                    |
+------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Language_Phrases | CREATE TABLE `Language_Phrases` (
  `Language_Id` int(11) NOT NULL,
  `Phrase` varchar(255) DEFAULT NULL,
  `Label` varchar(255) NOT NULL,
  PRIMARY KEY (`Language_Id`,`Label`),
  KEY `FK8B4876F3AEC1DBE9` (`Language_Id`),
  CONSTRAINT `FK8B4876F3AEC1DBE9` FOREIGN KEY (`Language_Id`) REFERENCES `Language` (`Id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select * from Language;
+----+------+----------+---------+------------+
| Id | Code | Name     | Variant | Country_Id |
+----+------+----------+---------+------------+
|  1 | en   | English  |         |        235 |
|  2 | ro   | Romanian |         |        181 |
+----+------+----------+---------+------------+
2 rows in set (0.00 sec)

mysql> select * from Language_Phrases;
Empty set (0.00 sec)

mysql> INSERT INTO Language_Phrases (Language_Id, Label, Phrase) VALUES (1, 'exampleLabel', 'Some phrase');
ERROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`dev`.`language_phrases`, CONSTRAINT `FK8B4876F3AEC1DBE9` FOREIGN KEY (`Language_Id`) REFERENCES `Language` (`Id`))
mysql> 

UPDATE: After dropping and recreating the database several times, I did a show engine innodb status after the failing insert above and got this surprising result. The parent Language table is not found! This seems very strange... any ideas?

------------------------
LATEST FOREIGN KEY ERROR
------------------------
110406  9:55:49 Transaction:
TRANSACTION CA3B, ACTIVE 0 sec, OS thread id 4494462976 inserting
mysql tables in use 1, locked 1
1 lock struct(s), heap size 376, 0 row lock(s)
MySQL thread id 25, query id 50720 localhost root update
INSERT INTO Language_Phrases (Language_Id, Label, Phrase) VALUES (1, 'exampleLabel', 'Some phrase')
Foreign key constraint fails for table `dev`.`language_phrases`:
,
  CONSTRAINT `FK8B4876F3AEC1DBE9` FOREIGN KEY (`Language_Id`) REFERENCES `Language` (`Id`)
Trying to add to index `PRIMARY` tuple:
DATA TUPLE: 5 fields;
 0: len 4; hex 80000001; asc     ;;
 1: len 17; hex 747970654d69736d617463682e79656172; asc exampleLabel;;
 2: len 6; hex 00000000ca3b; asc      ;;;
 3: len 7; hex 00000000000000; asc        ;;
 4: len 21; hex 59656172206d7573742062652061206e756d626572; asc Some phrase;;

But the parent table `dev`.`Language`
or its .ibd file does not currently exist!

UPDATE 2: It turns out this is simply a massive bug in MySQL. Apparently the latest versions of MySQL do not work fully under mac os X 10.6 (maybe earlier versions too?). Downgrading to 5.5.8 seems to work. Extremely surprising.

Answer 1

This does appear to be a bug introduced since MySQL 5.5.9 on Mac OS X: http://bugs.mysql.com/bug.php?id=60309

It is marked as fixed in 5.5.13 (released May 31) and mentioned in the release notes: http://dev.mysql.com/doc/refman/5.5/en/news-5-5-13.html

Alternatively, there is a workaround listed in the bug report that I've verified on 5.5.10 and reproduced below:

[20 Mar 11:29] Harald Neiss

I also received a new MBP and reinstalled MySQL (mysql-5.5.10-osx10.6-x86_64). Finally I
came across the same problem as described above. So here is the query result and what I
did to solve it.

mysql> show variables like 'lower%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| lower_case_file_system | ON    |
| lower_case_table_names | 2     |
+------------------------+-------+
2 rows in set (0.00 sec)

Dropped database, created the file /etc/my.cnf with the following content:

[mysqld]
lower_case_table_names=1

Restarted the MySQL daemon and repeated the query:

mysql> show variables like 'lower%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| lower_case_file_system | ON    |
| lower_case_table_names | 1     |
+------------------------+-------+
2 rows in set (0.00 sec)

I recreated the tables and everything works fine.