MySQL 5.5.x errno: 150 when renaming a primary key

[EikeDehling]

In a migration where a primary-key field is renamed, a mysql error occurs, because mysql needs foreign keys to be disabled/dropped for that operation.

See here for an example of the error you would get: ​http://stackoverflow.com/questions/4080611/1025-error-on-rename-of-database-sql-2e0f-1254ba7-to-database-table

I have a patch which fixes the issue: ​https://github.com/EikeDehling/django/commit/dbe0c4692fe1a7d73e4de345a171b8cbb35651b2

Please let me know what i can do to get this merged/fixed in django.

[Tim Graham]

A regression test in tests/schema is also needed.

[EikeDehling]

Commit with test here: ​https://github.com/EikeDehling/django/commit/72aa1b92551137da69104ab917079ea7e3ac8854

This would only fail on mysql though, which the test-framework does not use i think?

So the test also passes without my patch.

Suggestions?

[Tim Graham]

You need to ​create another settings file in order to run the tests with a different database. Please send a pull request with the fix and test.

[EikeDehling]

Thanks, testing with settings for mysql indeed shows the issue

[EikeDehling]

​https://github.com/django/django/pull/4881

[Tim Graham]

The current test on the pull request doesn't appear to be a regression test as it passes even with the fix reverted.

[Tim Graham]

As noted in ticket:26384#comment:16:

Prior to MySQL 5.6.6, adding and dropping a foreign key in the same ALTER TABLE statement may be problematic in some cases and is therefore unsupported. Separate statements should be used for each operation. As of MySQL 5.6.6, adding and dropping a foreign key in the same ALTER TABLE statement is supported for ALTER TABLE ... ALGORITHM=INPLACE but remains unsupported for ALTER TABLE ... ALGORITHM=COPY.

So the reason I didn't find the proposed test to be a regression test is because I'm using a newer version of MySQL. The test added in #26384 is similar to the one proposed in the pull request and has revealed the issue. Unfortunately both the test added in the other ticket and the test proposed in the pull request for this ticket are still failing on MySQL 5.5.x, even with the proposed fix (OperationalError: (1025, "Error on rename of './test_django/#sql-58c_2b9' to './test_django/schema_author' (errno: 150)")).

[Tim Graham <timograham@…>]

In f3595b2:

Refs #26384, #24995 -- Skipped a schema test on older MySQL versions.

[Tim Graham <timograham@…>]

In a0e3cbaa:

[1.9.x] Refs #26384, #24995 -- Skipped a schema test on older MySQL versions.

Backport of f3595b25496691966d4ff858a3b395735ad85a6e from master

[Tim Graham <timograham@…>]

In d81d02d:

Refs #26384, #24995 -- Avoided a module-level MySQL query in the schema tests.

[Tim Graham <timograham@…>]

In 5c1944f9:

[1.9.x] Refs #26384, #24995 -- Avoided a module-level MySQL query in the schema tests.

Backport of d81d02d449edd046a94de5f171f4ae87fa331c7d from master

[Tim Graham]

It looks like a patch isn't forthcoming and master will drop support for MySQL 5.5 following Django 2.0 alpha (#28552), so I think we can close this.