Detection of existing total ordering in admin changelist should take into account UniqueConstraints without conditions.

[Fabio Sangiovanni]

I've been fiddling with db indexes lately to improve the performance of an admin view.
Eventually I found this PR ​https://github.com/django/django/pull/10692 which ensures the records displayed by ChangeList are deterministically ordered.
Among other things, the code looks for the presence of a unique_together attribute on the Meta class of the model to determine if the model is already totally ordered.

I think that _get_deterministic_ordering() should check for the presence of UniqueConstraints as well, which currently aren’t considered by the discovery algorithm.

I noticed the docs currently advise against using unique_together in favor of UniqueConstraint, suggesting the former may be deprecated in the future, so this fix would change that part of the code accordingly.

I'm willing to submit a PR for this.

Cheers,
Fabio

[Mariusz Felisiak]

Agreed, we need to remember to ignore UniqueConstraint's with condition's.

[Fabio Sangiovanni]

PR: ​https://github.com/django/django/pull/12364

[Mariusz Felisiak <felisiak.mariusz@…>]

In d270c10a:

Refs #31187 -- Added total_unique_constraints property to model's Options.

[Mariusz Felisiak <felisiak.mariusz@…>]

In b457068c:

Fixed #31187 -- Fixed detecting of existing total ordering in admin changelist when using Meta.constraints.

Detection of existing total ordering in admin changelist now takes into
account non-partial unique constraints.