#12421: Foreign Key on Non-Primary Field fails due to lack of Index on Related
Field w/ MySQL
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Reporter: anonymous | Owner: nobody
Status: reopened | Milestone:
Component: Database layer (models, ORM) | Version: SVN
Resolution: | Keywords:
Stage: Accepted | Has_patch: 0
Needs_docs: 0 | Needs_tests: 0
Needs_better_patch: 0 |
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Changes (by clouserw):
* cc: [email protected] (added)
* status: closed => reopened
* resolution: worksforme =>
Comment:
I can reproduce this with the following model:
{{{
from django.db import models
class Item(models.Model):
license = models.ForeignKey('License', to_field="name", null=True)
class Meta:
db_table = 'testo_item'
class License(models.Model):
name = models.PositiveIntegerField(db_index=True)
class Meta:
db_table = 'testo_license'
}}}
An important point to note is that I'm forcing InnoDB in my settings.py
(which is the difference between this failing and not):
{{{
DATABASES = {
'default': {
...
'OPTIONS': {'init_command': 'SET storage_engine=InnoDB'},
},
}
}}}
At that point running sqlall will show you the order the commands are
executed:
{{{
$ ./manage.py sqlall testo
BEGIN;
CREATE TABLE `testo_item` (
`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
`license_id` integer UNSIGNED
)
;
CREATE TABLE `testo_license` (
`id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
`name` integer UNSIGNED
)
;
ALTER TABLE `testo_item` ADD CONSTRAINT `license_id_refs_name_a4fa988`
FOREIGN KEY (`license_id`) REFERENCES `testo_license` (`name`);
CREATE INDEX `testo_item_license_id` ON `testo_item` (`license_id`);
CREATE INDEX `testo_license_name` ON `testo_license` (`name`);
COMMIT;
}}}
Note that it's trying to add the foreign key before it creates the
indexes. Copying and pasting the above output will work fine, unless your
default table type is InnoDB (or you can modify the CREATE TABLE
statements and add ENGINE=InnoDB).
--
Ticket URL: <http://code.djangoproject.com/ticket/12421#comment:3>
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