#26476: Migration preserve_default does not works properly?
-------------------------------------+-------------------------------------
Reporter: madEng84 | Owner: nobody
Type: Bug | Status: closed
Component: Migrations | Version: 1.8
Severity: Normal | Resolution: invalid
Keywords: preserve_default | Triage Stage:
sqlmigrate | Unreviewed
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 shaib):
* status: new => closed
* resolution: => invalid
Comment:
If table `my_app_label` is not empty when you run this migration, and you
try to add a non-null column without a default, your database should give
an error. This is why Django uses a default in the transaction.
Your reading of the documentation is a bit too literal -- or, arguably,
the documentation is not clear enough; what is meant is that Django never
'''leaves''' defaults in the database.
Indeed, for large databases the aler-table queries (well, the first) could
be quite heavy. I am not aware of a light way to add a non-nullable column
to a large table.
In the future, please ask "is this a bug" type questions on a users'
forum, such as the #django IRC channel or django-users mailing list.
--
Ticket URL: <https://code.djangoproject.com/ticket/26476#comment:3>
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