[Django] #23556: Allow migrations to depend on a migration only part of a squashed migration
Django
-------------------------------+-------------------------
Reporter: Markush2010 | Owner: Markush2010
Type: Uncategorized | Status: new
Component: Migrations | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------+-------------------------
If a migration depends on another migration that is part of a squashed
migration (e.g. `6_auto` depends on `5_auto` which is part of
`3_squashed_5`) this leads to a `KeyError`:
{{{#!python
Traceback (most recent call last):
File "/home/markus/Coding/django/django/test/utils.py", line 216, in
inner
return test_func(*args, **kwargs)
File "/home/markus/Coding/django/tests/migrations/test_loader.py", line
263, in test_loading_squashed_complex2
loader.build_graph()
File "/home/markus/Coding/django/django/db/migrations/loader.py", line
233, in build_graph
self.graph.add_dependency(migration, key, parent)
File "/home/markus/Coding/django/django/db/migrations/graph.py", line
42, in add_dependency
raise KeyError("Migration %s dependencies reference nonexistent parent
node %r" % (migration, parent))
KeyError: "Migration migrations.6_auto dependencies reference nonexistent
parent node ('migrations', '5_auto')"
}}}
Thus the whole idea of `squashmigrations` to be able to remove old
migrations is not really working out since a 3rd party app might depend on
a specific migration.
I build a testcase:
https://github.com/Markush2010/django/commit/9a983d4fe66c583858eb370497d0b66227690f79
--
Ticket URL: <https://code.djangoproject.com/ticket/23556>
Django <https://code.djangoproject.com/>
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Django
Reporter: Markush2010 | Owner: Markush2010
Type: Bug | Status: new
Component: Migrations | Version: master
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 carljm):
* needs_better_patch: => 0
* needs_tests: => 0
* needs_docs: => 0
* type: Uncategorized => Bug
* stage: Unreviewed => Accepted
Old description:
New description:
If a migration depends on another migration that is part of a squashed
migration (e.g. `6_auto` depends on `5_auto` which is part of
`3_squashed_5`) removing the squashed migration (e.g. `5_auto`) leads to a
`KeyError`:
{{{#!python
Traceback (most recent call last):
File "/home/markus/Coding/django/django/test/utils.py", line 216, in
inner
return test_func(*args, **kwargs)
File "/home/markus/Coding/django/tests/migrations/test_loader.py", line
263, in test_loading_squashed_complex2
loader.build_graph()
File "/home/markus/Coding/django/django/db/migrations/loader.py", line
233, in build_graph
self.graph.add_dependency(migration, key, parent)
File "/home/markus/Coding/django/django/db/migrations/graph.py", line
42, in add_dependency
raise KeyError("Migration %s dependencies reference nonexistent parent
node %r" % (migration, parent))
KeyError: "Migration migrations.6_auto dependencies reference nonexistent
parent node ('migrations', '5_auto')"
}}}
Thus the whole idea of `squashmigrations` to be able to eventually remove
old migrations is not really working out since a 3rd party app might
depend on a specific migration.
I build a testcase:
https://github.com/Markush2010/django/commit/9a983d4fe66c583858eb370497d0b66227690f79
--
--
Ticket URL: <https://code.djangoproject.com/ticket/23556#comment:1>
Django
Reporter: Markush2010 | Owner: Markush2010
Type: Bug | Status: new
Component: Migrations | Version: master
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by carljm):
Markus' idea in IRC was that the migration system ought to be able to
detect that since `3_squashed_5` replaces `5_auto`, and `5_auto` is gone,
anything depending on `5_auto` should instead be automatically considered
to depend on `3_squashed_5` instead.
--
Ticket URL: <https://code.djangoproject.com/ticket/23556#comment:2>
Django
Reporter: Markush2010 | Owner:
Type: | Markush2010
Cleanup/optimization | Status: new
Component: Migrations | Version: master
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by Markush2010):
* type: Bug => Cleanup/optimization
Comment:
I looked into the issue a bit deeper and found my tests to be faulty. I'm
working on a patch to make the error message more useful, though.
--
Ticket URL: <https://code.djangoproject.com/ticket/23556#comment:3>
Django
Reporter: Markush2010 | Owner:
Type: | Markush2010
Component: Migrations | Version: master
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Markush2010):
I updated my tests and slightly changed the behavior of the migration
loader to check for if a migration could have potentially be replaced by a
squash migration, but which wasn't used due e.g. partially be applied.
E.g. if 3, 4 and 5 are squashed into 3_5 and a database has 3 applied, but
not 4 and 5, 3_5 cannot be used. In this case removing 3 or 4 from the
file system is not possible until 5 is applied on every instance.
Pull request: https://github.com/django/django/pull/3280
--
Ticket URL: <https://code.djangoproject.com/ticket/23556#comment:4>
Django
Reporter: Markush2010 | Owner:
Type: | Markush2010
Component: Migrations | Version: master
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by Markus Holtermann <info@…>):
* status: new => closed
* resolution: => fixed
Comment:
In [changeset:"85086c815873c4cf0bc2f1f2809119088cbe55f1"]:
{{{
#!CommitTicketReference repository=""
revision="85086c815873c4cf0bc2f1f2809119088cbe55f1"
Fixed #23556 -- Raised a more meaningful error message when migrations
refer to an unavailable node
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/23556#comment:5>
Django
Reporter: Markush2010 | Owner:
Type: | Markush2010
Cleanup/optimization | Status: closed
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by Andrew Godwin <andrew@…>):
In [changeset:"aac594f65f613929f904f2ecb466edfb573e17b4"]:
{{{
#!CommitTicketReference repository=""
revision="aac594f65f613929f904f2ecb466edfb573e17b4"
Merge pull request #3280 from Markush2010/ticket23556
Fixed #23556 -- Raise a more meaningful error message when migrations
refer to an unavailable node
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/23556#comment:6>