Migrations "fail" when using MSSQL as database

[ivissani]

Describe the bug
An exception is thrown when running migrations using MSSQL as database backend. The error reported by SQL Server is the following:

The operation failed because an index or statistics with name 'rest_framework_api_key_apikey_prefix_4e0db5f8_uniq' already exists on table 'rest_framework_api_key_apikey'. (1913) (SQLExecDirectW).

Looking at the code in AbstractAPI I conjecture that the error is produced because of the definition of the id field:

id = models.CharField(max_length=100, unique=True, primary_key=True, editable=False)

My guess is that, for some reason, SQL Server is actually trying to create two times the same index because both primary_key AND unique are set to true. Even though this is probably a bug in django-mssql-backend, I'm reporting this here because it's my understanding that primary_key already implies unique and therefore it should not be necessary to set unique. Am I right?

To Reproduce
Steps to reproduce the behavior:

1. Set up a django project using django-mssql-backend as database backend and djangorestframework-api-key
2. Run migrations
3. See error

Desktop (please complete the following information):

• OS: Linux and OSX
• Python Version: 3.7
• Django Version: 2.2
• Django Rest Framework APIKey Version: 2.0.0
• DRF Version: 3.11.0
• django-mssql-backend Version: 2.8.1

[florimondmanca]

Hi,

It's my understanding that primary_key already implies unique and therefore it should not be necessary to set unique. Am I right?

Sounds fair. 🤔 Does removing unique=True allow your migration to pass?

[ivissani]

Actually not... and the exception comes from this 0004_prefix_hashed_key migration, so it seems has nothing to do with combining primary_key with unique.
I will do a more thorough research and get back with better insight. At this point it seems to be django-mssql-backend's fault completely.

[ivissani]

I'm closing this since is not related to this package. The fault was actually an issue in django-mssql-backend: ESSolutions/django-mssql-backend#75