#23273: MigrationRecorder does not obey db_router allow_migrate rules
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Reporter: froomzy | Owner: nobody
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
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Changes (by marfire):
* cc: k@… (added)
* version: 1.7 => master
Comment:
I wanted to chime in here to broaden the scope of the bug, as I was
affected by it recently in a different context.
The bigger issue is not just that the framework tries to create the
migrations table where it's not needed, but that it marks as applied
migrations that in fact were not. That puts the database in an
inconsistent state, at least as far as migrations are concerned. It's a
harmless inconsistency for the specific settings file used at that
specific moment in time, but it lays the seed for big problems down the
line. For example, if you later decide to change your routing scheme, or
(as happened in my case) if you have multiple projects with different
settings using the same app on the same database.
In terms of a solution, what seems straightforward to my untrained eye is
for the migration framework to simply not record migrations as applied
that it didn't apply (and as a corollary, it shouldn't try to create the
migration table on a database if it doesn't need to record any migrations
there). The fix suggested above ("to have migrations refuse to run
entirely and just exit if the migration model is not allowed to be created
on the target database") doesn't address the broader issue.
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Ticket URL: <https://code.djangoproject.com/ticket/23273#comment:13>
Django <https://code.djangoproject.com/>
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