#31320: Prevent BEGIN and COMMIT in RunSQL in atomic migrations.
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Reporter: Adam (Chainz) | Owner: nobody
Johnson |
Type: New feature | Status: closed
Component: Migrations | Version: master
Severity: Normal | Resolution: wontfix
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Simon Charette):
> The reason I made this was when squashing migrations on a client
project, it had some RunSQL operations in migrations that worked fine
alone, but when the operatiosn were squashed together it broke the
squashed migration's transactional state.
Interesting, were these migrations marked `atomic = False` initially? It
looks like
[https://github.com/django/django/blob/2bd8df243ac6fc35e58c9fe90b20c9e42519a5ac/django/core/management/commands/squashmigrations.py#L165-L170
the current code] completely ignores this flag. I guess the command could
at least warn about it.
Migration squashing is definitely an area that would benefit from a bit of
love wrt to dependency resolving and could be a good GSOC project in the
next years if we ever apply.
From [https://docs.djangoproject.com/en/3.0/topics/migrations/#migration-
squashing the docs themselves]
> To manually resolve a CircularDependencyError, break out one of the
ForeignKeys in the circular dependency loop into a separate migration, and
move the dependency on the other app with it. If you’re unsure, see how
makemigrations deals with the problem when asked to create brand new
migrations from your models. **In a future release of Django,
squashmigrations will be updated to attempt to resolve these errors
itself.**
It looks like non-atomic migrations pose a similar problem where they'd
need to be considered an optimization barrier and require the creation of
a standalone migration.
--
Ticket URL: <https://code.djangoproject.com/ticket/31320#comment:5>
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