Opened 8 years ago
Closed 8 years ago
#26535 closed Uncategorized (worksforme)
Possible bug - when migrating and removing unique constraint.
Reported by: | jenlu | Owned by: | nobody |
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Component: | Migrations | Version: | 1.9 |
Severity: | Normal | Keywords: | |
Cc: | Triage Stage: | Unreviewed | |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description (last modified by )
Possible bug - when migrating and removing unique constraint.
Postgres 9.4.1 / 9.5.7 + Django 1.9.5 + psycopg 2.6.1
——
My setup is models/database representing sports events, and with competitors in different events.
Each competitor in different sports has for their model/class:
class Meta: unique_together = ('event', 'number')
i.e. ensure a unique starting number in an event, now we are relaxing (removing this constraint)
this but having issues when migrating.
The above is represented in postgress as a UNIQUE constraint
and in all models.py the above constraint is as-above — but in pg it is represented as
(i) UNIQUE (event_id, number)
and sometimes as...
(ii) UNIQUE (number, event_id)
…and now when doing migration - for all tables where it is represented as (i) everything
goes well, but in tables where (ii) the following error:
File "/Users/XXX/.virtualenvs/ssi195_2711/lib/python2.7/site-packages/django/db/migrations/migration.py", line 123, in apply operation.database_forwards(self.app_label, schema_editor, old_state, project_state) File "/Users/XXX/.virtualenvs/ssi195_2711/lib/python2.7/site-packages/django/db/migrations/operations/models.py", line 359, in database_forwards getattr(new_model._meta, self.option_name, set()), File "/Users/XXX/.virtualenvs/ssi195_2711/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 318, in alter_unique_together self._delete_composed_index(model, fields, {'unique': True}, self.sql_delete_unique) File "/Users/XXX/.virtualenvs/ssi195_2711/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 347, in _delete_composed_index ", ".join(columns), ValueError: Found wrong number (0) of constraints for match_ppc_ppccompetitor(event_id, number)
So seems to need to do some migrations manually and no biggie - but yet strange and unsure if Django or pg issue….
/ Jens
Change History (3)
comment:1 by , 8 years ago
Description: | modified (diff) |
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comment:2 by , 8 years ago
Hi, did some test but unable to reproduce in my ‘current’ setup - it always generates a
uniqueness constraint that can be removed.
Seems like my oldest models did generate one ordering in pg (UNIQUE(number, event_id)
whereas models added later on did generate the different ordering in pq (UNIQUE(event_id,
number) and this later have no problems to be removed/relaxed.
Not sure if under 1.7 or might have been even earlier that these models with this issue was added.
Workaround for me was just to DROP the constraint and add a new one with same arguments
but in different order..
/ Jens
comment:3 by , 8 years ago
Resolution: | → worksforme |
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Status: | new → closed |
Could you provide a sample project that reproduces the issue?