Renaming fields with truncated names don't remove old constraints on Oracle.

[Georgi Yanchev]

Steps to reproduce:

1. Use Oracle as a db backend

2. Create a model class:

   class TestModel(models.Model):
       looooooooooooooooooooooooooooooooooooooong_name = models.PositiveIntegerField(default=0)
   

3. python manage.py makemigrations

You get a migration file called 0001_initial.py with:

    operations = [
        migrations.CreateModel(
            name='TestModel',
            fields=[
                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('looooooooooooooooooooooooooooooooooooooong_name', models.PositiveIntegerField(default=0)),
            ],
        ),
    ]

4. Rename the field in the model:

   class TestModel(models.Model):
       renamed_looooooooooooooooooooooooooooooooooooooong_name = models.PositiveIntegerField(default=0)
   

5. python manage.py makemigrations

When asked about whether the field was renamed, say "y".
You get another migrations file 0002_rename_looooooooooooooooooooooooooooooooooooooong_name_testmodel_renamed_loooooooooooooooooooooooooo.py with:

    operations = [
        migrations.RenameField(
            model_name='testmodel',
            old_name='looooooooooooooooooooooooooooooooooooooong_name',
            new_name='renamed_looooooooooooooooooooooooooooooooooooooong_name',
        ),
    ]

6. Migrate db

python manage.py migrate myapp
The queries executed are:

-- 0001_....py
CREATE TABLE "MYAPP_TESTMODEL" ("ID" NUMBER(19) GENERATED BY DEFAULT ON NULL AS IDENTITY NOT NULL PRIMARY KEY, "LOOOOOOOOOOOOOOOOOOOOOOOOO8973" NUMBER(11) NOT NULL CHECK ("LOOOOOOOOOOOOOOOOOOOOOOOOO8973" >= 0))

-- 0002_....py
ALTER TABLE "MYAPP_TESTMODEL" RENAME COLUMN "LOOOOOOOOOOOOOOOOOOOOOOOOO8973" TO "RENAMED_LOOOOOOOOOOOOOOOOOAFEA"
ALTER TABLE "MYAPP_TESTMODEL" ADD CONSTRAINT "MYAPP_TES_RENAMED_L_7E971FCA_C" CHECK ("RENAMED_LOOOOOOOOOOOOOOOOOAFEA" >= 0)

Note that we didn't create a constraint when applying 0001, but we did create one for 0002. So the db schema is not the same as it would be if 0001 and 0002 were squashed

7. Unapply 0002

python manage.py migrate myapp 0001
Queries are:

ALTER TABLE "MYAPP_TESTMODEL" RENAME COLUMN "RENAMED_LOOOOOOOOOOOOOOOOOAFEA" TO "LOOOOOOOOOOOOOOOOOOOOOOOOO8973"
ALTER TABLE "MYAPP_TESTMODEL" ADD CONSTRAINT "MYAPP_TES_LOOOOOOOO_D76B28D1_C" CHECK ("LOOOOOOOOOOOOOOOOOOOOOOOOO8973" >= 0)

Note that MYAPP_TES_RENAMED_L_7E971FCA_C that was created when 0002 was applied is not dropped. So now we end up with 2 CONSTRAINTs.

8. Apply 0002

python migrate myapp 0002

Queries are:

ALTER TABLE "MYAPP_TESTMODEL" RENAME COLUMN "LOOOOOOOOOOOOOOOOOOOOOOOOO8973" TO "RENAMED_LOOOOOOOOOOOOOOOOOAFEA"
ALTER TABLE "MYAPP_TESTMODEL" ADD CONSTRAINT "MYAPP_TES_RENAMED_L_7E971FCA_C" CHECK ("RENAMED_LOOOOOOOOOOOOOOOOOAFEA" >= 0)

Observed:

The last query fails with:

django.db.utils.DatabaseError: ORA-02264: name already used by an existing constraint

Expected:

1. Database schema is the same no matter whether a field was renamed.
2. Obsolete db CONSTRAINTs are dropped.

[Mariusz Felisiak]

Thanks for the report. As far as I'm aware, the main reason is that BaseDatabaseSchemaEditor._constraint_names() ​doesn't use truncated column names.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 6bdc3c58:

Fixed #34320 -- Make sure constraints names are obtained from truncated columns names.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 3b09f355:

[4.2.x] Fixed #34320 -- Make sure constraints names are obtained from truncated columns names.

Backport of 6bdc3c58b65eb32fd63cd41849f00a17a36b4473 from main

[GitHub <noreply@…>]

In 40e88ae:

Refs #34320 -- Added skipIf for a test requiring check constraints.

[Mariusz Felisiak <felisiak.mariusz@…>]

In fae76b81:

[4.2.x] Refs #34320 -- Added skipIf for a test requiring check constraints.

Backport of 40e88ae8c899bcae3a9520f7a6519dd178185f85 from main

[GitHub <noreply@…>]

In 9953c804:

Refs #34320 -- Stopped recreating check constraints when renaming fields.

This also fixes test_rename_field_with_check_to_truncated_name() on
MariaDB 10.5.2+ as ALTER TABLE ... RENAME COLUMN statement doesn't
rename inline constraints.

[GitHub <noreply@…>]

In fec4ed0a:

[4.2.x] Refs #34320 -- Skipped SchemaTests.test_rename_field_with_check_to_truncated_name on MariaBD 10.5.2+.

This crashes since MariaDB was bumped to 10.5 on Jenkins.