Opened 4 years ago

Closed 4 years ago

Last modified 4 years ago

#22844 closed Bug (fixed)

SQLite3 migrations fail with unique_together on a ForeignKey

Reported by: fongandrew Owned by: Andrew Godwin
Component: Migrations Version: 1.7-beta-2
Severity: Release blocker Keywords: migrations, sqlite
Cc: Triage Stage: Accepted
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no



from django.db import models
from django.contrib.auth.models import User

class DropboxAccount(models.Model):
    A Dropbox account linked to an existing user account
    user = models.ForeignKey(User)
    dropbox_uid = models.CharField(max_length=32)
    class Meta:
        unique_together = (
            ("user", "dropbox_uid"),

creates the following exception during migration:

Creating test database for alias 'default'...
Traceback (most recent call last):
  File "", line 10, in <module>
  File "/home/vagrant/deployment/src/django/django/core/management/", line 385, in execute_from_command_line
  File "/home/vagrant/deployment/src/django/django/core/management/", line 377, in execute
  File "/home/vagrant/deployment/src/django/django/core/management/commands/", line 50, in run_from_argv
    super(Command, self).run_from_argv(argv)
  File "/home/vagrant/deployment/src/django/django/core/management/", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/vagrant/deployment/src/django/django/core/management/commands/", line 71, in execute
    super(Command, self).execute(*args, **options)
  File "/home/vagrant/deployment/src/django/django/core/management/", line 337, in execute
    output = self.handle(*args, **options)
  File "/home/vagrant/deployment/src/django/django/core/management/commands/", line 88, in handle
    failures = test_runner.run_tests(test_labels)
  File "/home/vagrant/deployment/src/django/django/test/", line 147, in run_tests
    old_config = self.setup_databases()
  File "/home/vagrant/deployment/src/django/django/test/", line 109, in setup_databases
    return setup_databases(self.verbosity, self.interactive, **kwargs)
  File "/home/vagrant/deployment/src/django/django/test/", line 299, in setup_databases
    serialize=connection.settings_dict.get("TEST_SERIALIZE", True),
  File "/home/vagrant/deployment/src/django/django/db/backends/", line 373, in create_test_db
  File "/home/vagrant/deployment/src/django/django/core/management/", line 115, in call_command
    return klass.execute(*args, **defaults)
  File "/home/vagrant/deployment/src/django/django/core/management/", line 337, in execute
    output = self.handle(*args, **options)
  File "/home/vagrant/deployment/src/django/django/core/management/commands/", line 146, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/home/vagrant/deployment/src/django/django/db/migrations/", line 62, in migrate
    self.apply_migration(migration, fake=fake)
  File "/home/vagrant/deployment/src/django/django/db/migrations/", line 96, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/home/vagrant/deployment/src/django/django/db/migrations/", line 107, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/home/vagrant/deployment/src/django/django/db/migrations/operations/", line 238, in database_forwards
    getattr(new_model._meta, "unique_together", set()),
  File "/home/vagrant/deployment/src/django/django/db/backends/sqlite3/", line 169, in alter_unique_together
    self._remake_table(model, override_uniques=new_unique_together)
  File "/home/vagrant/deployment/src/django/django/db/backends/sqlite3/", line 126, in _remake_table
    self.execute(sql.replace(temp_model._meta.db_table, model._meta.db_table))
  File "/home/vagrant/deployment/src/django/django/db/backends/", line 98, in execute
    cursor.execute(sql, params)
  File "/home/vagrant/deployment/src/django/django/db/backends/", line 65, in execute
    return self.cursor.execute(sql, params)
  File "/home/vagrant/deployment/src/django/django/db/", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/home/vagrant/deployment/src/django/django/db/backends/", line 65, in execute
    return self.cursor.execute(sql, params)
  File "/home/vagrant/deployment/src/django/django/db/backends/sqlite3/", line 485, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: index dropbox__dropboxaccount_e8701ad4 already exists

As far as I can tell, the issue is that Django is creating two identically-named indices: one for the ForeignKey and one for the unique_together constraint. This issue does not occur if I add db_index=False to the ForeignKey or remove the unique_together constraint.

Change History (4)

comment:1 Changed 4 years ago by Tim Graham

Component: UncategorizedMigrations
Severity: NormalRelease blocker
Triage Stage: UnreviewedAccepted
Type: UncategorizedBug

I can reproduce on the latest master.

comment:2 Changed 4 years ago by Andrew Godwin

Owner: changed from nobody to Andrew Godwin
Status: newassigned

Looking at this now.

comment:3 Changed 4 years ago by Andrew Godwin <andrew@…>

Resolution: fixed
Status: assignedclosed

In d4305a15c1d48a0248ce1da1989a145009029e6c:

[1.7.x] Fixed #22844: Duplicate SQL for SQLite FKs

comment:4 Changed 4 years ago by anonymous

Disclaimer: This comment is mainly for South users who arrive here after searching Google for django migrate sqlite3 unique_together

This is the only reference I can find of this anywhere, other than a couple of five year old bug report on South ( and and #21236 which seems related to this patch.

The only solution that I could find for this using South-0.8.4 and Django-1.6.5 was to remove the unique_together Meta option, migrate, add the changes to the model, migrate, and the re-add unique_together and migrate one last time.

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