#24630: Misleading/incorrect docs about RunPython and transactions
-------------------------------------+-------------------------------------
Reporter: lucacorti | Owner:
| priidukull
Type: Bug | Status: new
Component: Documentation | Version: 1.8
Severity: Release blocker | Resolution:
Keywords: uuidfiled | Triage Stage: Accepted
migrations |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Changes (by timgraham):
* stage: Unreviewed => Accepted
* component: Migrations => Documentation
* severity: Normal => Release blocker
Comment:
It seems to me that the documentation that says, "By default, RunPython
will run its contents inside a transaction" is misleading (added in
5a917cfef319df33ca30a3b27bd0b0533b8e63bb).
Each *migration* is run in its own transaction (if the database backend
has `can_rollback_ddl = True`) because we use
[https://github.com/django/django/blob/1418f7530455abf3e6f743164ae15ee6b2566a3c/django/db/migrations/executor.py#L122-L128
a SchemaEditor context manager] when applying each migration, which
[https://github.com/django/django/commit/e74d2183c28467aefc0b87e3fa6d405dbfdea82c
creates a transaction].
I'm not sure we can make any changes code-wise to support mixing schema
changes and RunPython operations in the same migration, but we should
correct the documentation for current version of Django anyway.
Docs to fix:
* The second example migration needs to be split into at least two
migrations. https://docs.djangoproject.com/en/1.8/howto/writing-migrations
/#migrations-that-add-unique-fields
* "By default, RunPython will run its contents..."
https://docs.djangoproject.com/en/1.8/ref/migration-operations/#runpython
--
Ticket URL: <https://code.djangoproject.com/ticket/24630#comment:10>
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