#27245: can't revert migration with index_together with one field
-------------------------------+--------------------
Reporter: rm_ | Owner: nobody
Type: Bug | Status: new
Component: Uncategorized | Version: 1.8
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------+--------------------
With django 1.8.14 i added a composite index with one field (lame, sorry!)
because the field is from an abstract model and it seemed the cleanest way
to handle that:
{{{
+ class Meta:
+ index_together = ['owner']
}}}
The migrations got created and applied finely:
{{{
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import migrations, models
class Migration(migrations.Migration):
dependencies = [
('foobar', '0002_auto_20160315_1805'),
]
operations = [
migrations.AlterIndexTogether(
name='answer',
index_together=set([('owner',)]),
),
]
}}}
Problem is i can't revert the migration:
{{{
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/venv/local/lib/python2.7/site-
packages/django/core/management/__init__.py", line 354, in
execute_from_command_line
utility.execute()
File "/venv/local/lib/python2.7/site-
packages/django/core/management/__init__.py", line 346, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/venv/local/lib/python2.7/site-
packages/django/core/management/base.py", line 394, in run_from_argv
self.execute(*args, **cmd_options)
File "/venv/local/lib/python2.7/site-
packages/django/core/management/base.py", line 445, in execute
output = self.handle(*args, **options)
File "/venv/local/lib/python2.7/site-
packages/django/core/management/commands/migrate.py", line 222, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/venv/local/lib/python2.7/site-
packages/django/db/migrations/executor.py", line 112, in migrate
self.unapply_migration(states[migration], migration, fake=fake)
File "/venv/local/lib/python2.7/site-
packages/django/db/migrations/executor.py", line 168, in unapply_migration
state = migration.unapply(state, schema_editor)
File "/venv/local/lib/python2.7/site-
packages/django/db/migrations/migration.py", line 162, in unapply
operation.database_backwards(self.app_label, schema_editor,
from_state, to_state)
File "/venv/local/lib/python2.7/site-
packages/django/db/migrations/operations/models.py", line 415, in
database_backwards
return self.database_forwards(app_label, schema_editor, from_state,
to_state)
File "/venv/local/lib/python2.7/site-
packages/django/db/migrations/operations/models.py", line 411, in
database_forwards
getattr(new_model._meta, self.option_name, set()),
File "/venv/local/lib/python2.7/site-
packages/django/db/backends/base/schema.py", line 336, in
alter_index_together
self._delete_composed_index(model, fields, {'index': True},
self.sql_delete_index)
File "venv/local/lib/python2.7/site-
packages/django/db/backends/base/schema.py", line 349, in
_delete_composed_index
", ".join(columns),
ValueError: Found wrong number (2) of constraints for
cicero_academy_answeracademy(owner_id)
}}}
So the easy way to fix this is to don't permit te creation of a migration
with less than two fields. OTOH it would be quite cool to use the non
composite way of removing an index if the constraints are not enough.
Whatever you decide i can spend some time on the fix.
--
Ticket URL: <https://code.djangoproject.com/ticket/27245>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
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