[Django] #35038: Changing violation_error_message on constraints cause a remove/add operation in migration

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
------------------------------------------------+------------------------
Reporter: David | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Migrations | Version: 4.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
------------------------------------------------+------------------------
Changing the `violation_error_message` of a constraint and running
`makemigrations` causes the migration to be written with two operations
`RemoveConstraint` and `AddConstraint `.

Suppose we start with this situation:
{{{
#!python
from django.db import models

class MyModel(models.Model):
counter = models.IntegerField(defalt=0)
max_value = models.IntegerField(defalt=0)
name = models.CharField(max_length=4)

class Meta:
constraints = (
models.CheckConstraint(
check=models.Q(counter__gte=models.F('max_value')),
name='counter_lower_than_max',
),
models.UniqueConstraint(
fields=('name', 'max_value')
name='uniq_name_and_max',
),
)
}}}

If we add a custom `violation_error_message` and run `makemigrations` it
will output

{{{
$ ./manage.py makemigrations mysample -n update_violation_msgs
Migrations for 'mysample':
mysample/migrations/0002_update_violation_msgs.py
- Remove constraint counter_lower_than_max from model mymodel
- Create constraint counter_lower_than_max on model mymodel
- Remove constraint uniq_name_and_maxfrom model mymodel
- Create constraint uniq_name_and_maxon model mymodel
}}}

This will cause the database tu run useless commands, since nothing on
database side has changed!
This may be a particular problem when applied to `UniqueConstraint`s since
the database needs to destroy and re-create an index.

--
Ticket URL: <https://code.djangoproject.com/ticket/35038>
Django <https://code.djangoproject.com/>
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[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration

--------------------------------------+------------------------------------

Reporter: David | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Migrations | Version: 4.1

Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

--------------------------------------+------------------------------------
Changes (by David Sanders):

* stage: Unreviewed => Accepted

Comment:

Thanks for the report 🏆

Aside from running useless commands, dropping & adding constraints on a
production database may be undesirable.

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:1>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
--------------------------------------+------------------------------------
Reporter: David | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------------+------------------------------------

Changes (by Salvo Polizzi):

* has_patch: 0 => 1

Comment:

PR: https://github.com/django/django/pull/17644

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:2>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
--------------------------------------+------------------------------------
Reporter: David | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 0 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------------+------------------------------------

Changes (by Mariusz Felisiak):

* has_patch: 1 => 0

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:3>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration

-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned

Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

-------------------------------------+-------------------------------------
Changes (by Salvo Polizzi):

* owner: nobody => Salvo Polizzi
* status: new => assigned

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:4>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration

--------------------------------------+------------------------------------
Reporter: David | Owner: (none)
Type: Cleanup/optimization | Status: new

Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

--------------------------------------+------------------------------------
Changes (by Salvo Polizzi):

* owner: Salvo Polizzi => (none)
* status: assigned => new

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:5>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration

-------------------------------------+-------------------------------------
Reporter: David | Owner: Nathaniel
Type: | Conroy
Cleanup/optimization | Status: assigned

Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

-------------------------------------+-------------------------------------
Changes (by Nathaniel Conroy):

* owner: (none) => Nathaniel Conroy

* status: new => assigned

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:6>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration

--------------------------------------+------------------------------------
Reporter: David | Owner: (none)
Type: Cleanup/optimization | Status: new

Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

--------------------------------------+------------------------------------
Changes (by Nathaniel Conroy):

* owner: Nathaniel Conroy => (none)

* status: assigned => new

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:7>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration

-------------------------------------+-------------------------------------
Reporter: David | Owner: Adrienne
Type: | Franke
Cleanup/optimization | Status: assigned

Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0

-------------------------------------+-------------------------------------
Changes (by Adrienne Franke):

* owner: (none) => Adrienne Franke

* status: new => assigned

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:8>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Adrienne
Type: | Franke
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Adrienne Franke):

* cc: Adrienne Franke (added)

* has_patch: 0 => 1

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:9>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Adrienne
Type: | Franke
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0

Needs tests: 1 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* needs_better_patch: 0 => 1
* needs_tests: 0 => 1

Comment:

Marking as needs improvement pending a discussion.
--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:10>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Adrienne
Type: | Franke
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Shubham Singh Sugara):

Hi team ,
Is anyone working on this i think another issue (ticket ) is also waiting
for this to resolve (#35305)
willing to have a crack at it, open to dicussion
old PR closed with this comment on commit , maybe we can start from here ,
like what is the correct way to implement this patch ?
https://github.com/django/django/pull/17644/commits/fe9fa7ff28abc5a5a5bd70b93a1d8452ec1b5332#r1435873636
--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:11>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Adrienne
Type: | Franke
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Jacob Walls):

I think the latest
[https://github.com/django/django/pull/17846#issuecomment-1949371939
consensus] is that we need a new `Operation` for `AlterConstraint` that is
documented to be a no-op (emits no SQL) and that the migration framework
will produce in these cases in order to avoid dropping and recreating
constraints on the database.
--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:12>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------

Reporter: David | Owner: Salvo
Type: | Polizzi

Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 1 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Salvo Polizzi):

* owner: Adrienne Franke => Salvo Polizzi

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:13>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 1

Needs tests: 1 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Salvo Polizzi):

* needs_docs: 0 => 1

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:14>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 1

Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Salvo Polizzi):

* needs_tests: 1 => 0

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:15>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 1

Needs tests: 0 | Patch needs improvement: 0

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Salvo Polizzi):

* needs_better_patch: 1 => 0

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:16>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Salvo Polizzi):

* needs_docs: 1 => 0

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:17>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Sarah Boyce):

* needs_better_patch: 0 => 1

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:18>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Jacob Walls):

* needs_better_patch: 1 => 0

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:19>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Sarah Boyce):

* needs_better_patch: 0 => 1

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:20>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0

Needs tests: 1 | Patch needs improvement: 0

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Jacob Walls):

* needs_better_patch: 1 => 0

* needs_tests: 0 => 1

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:21>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:

Keywords: | Triage Stage: Ready for
| checkin

Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Jacob Walls):

* needs_tests: 1 => 0
* stage: Accepted => Ready for checkin

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:22>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: assigned
Component: Migrations | Version: 4.1
Severity: Normal | Resolution:
Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by Sarah Boyce <42296566+sarahboyce@…>):

In [changeset:"b92511b47475ce7fa1626d7d8c6180ae84bf0a19" b92511b4]:
{{{#!CommitTicketReference repository=""
revision="b92511b47475ce7fa1626d7d8c6180ae84bf0a19"
Refs #35038 -- Added test for drop and recreation of a constraint.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:23>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi

Cleanup/optimization | Status: closed
Component: Migrations | Version: 4.1
Severity: Normal | Resolution: fixed

Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Sarah Boyce <42296566+sarahboyce@…>):

* resolution: => fixed
* status: assigned => closed

Comment:

In [changeset:"b82f80906a563741e34aecac537b53c19945a44f" b82f8090]:
{{{#!CommitTicketReference repository=""
revision="b82f80906a563741e34aecac537b53c19945a44f"
Fixed #35038 -- Created AlterConstraint operation.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:24>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: closed
Component: Migrations | Version: 4.1
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 1

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Mariusz Felisiak):

* needs_better_patch: 0 => 1

Comment:

Please check
`lookup.tests.LookupTests.test_in_bulk_preserve_ordering_with_batch_size`
failure on PostgreSQL.
--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:25>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: closed
Component: Migrations | Version: 4.1
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Comment (by GitHub <noreply@…>):

In [changeset:"56f468681aaedefcdada1b86c441c12ae96e7fea" 56f4686]:
{{{#!CommitTicketReference repository=""
revision="56f468681aaedefcdada1b86c441c12ae96e7fea"
Refs #35038 -- Reduced CreateModel/AlterConstraint operations when
optimizing migrations.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:26>

[Django]

#35038: Changing violation_error_message on constraints cause a remove/add
operation in migration
-------------------------------------+-------------------------------------
Reporter: David | Owner: Salvo
Type: | Polizzi
Cleanup/optimization | Status: closed
Component: Migrations | Version: 4.1
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Ready for
| checkin
Has patch: 1 | Needs documentation: 0

Needs tests: 0 | Patch needs improvement: 0

Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------

Changes (by Jacob Walls):

* needs_better_patch: 1 => 0

--
Ticket URL: <https://code.djangoproject.com/ticket/35038#comment:27>