#34701: Add support for NULLS [NOT] DISTINCT to UniqueConstraint
-------------------------------------+-------------------------------------
Reporter: Simon Charette | Owner: nobody
Type: New feature | Status: assigned
Component: Database layer | Version: 4.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Simon Charette:
Old description:
> PostgresSQL 15 is one of the first databases to implement the F292 SQL
> feature present in the 2023 standard that allows to specify whether or
> not null values should be considered as distinct in unique constraints.
>
> While most backends default to implicit `NULLS DISTINCT` some backends
> don't, most notably SQL Server
> (cff59bedc23fd4d53557f677ddc42402b56963d0).
>
> I suggest we add a `nulls_distinct: Optional[bool]=None` option to
> `UniqueConstraint` so it preserves it's ''default to backend treatment of
> nulls'' behaviour while allowing it to be set explicitly on backends that
> support it.
>
> - [https://modern-sql.com/caniuse/unique-nulls-not-distinct Article on
> the subject]
> - [https://modern-sql.com/caniuse/F292 SQL:F292]
> - [https://forum.djangoproject.com/t/support-nulls-not-distinct-
> postgres-15-clause/21973/3 Recent thread on the subject in the forums]
New description:
PostgresSQL 15 is one of the first databases to implement the F292 SQL
feature present in the 2023 standard that allows to specify whether or not
null values should be considered as distinct in unique constraints.
While most backends default to implicit `NULLS DISTINCT` some backends
don't, most notably SQL Server (cff59bedc23fd4d53557f677ddc42402b56963d0).
I suggest we add a `nulls_distinct:Optional[bool]=None` option to
`UniqueConstraint` so it preserves it's ''default to backend treatment of
nulls'' behaviour while allowing it to be set explicitly on backends that
support it.
- [https://modern-sql.com/caniuse/unique-nulls-not-distinct Article on the
subject]
- [https://modern-sql.com/caniuse/F292 SQL:F292]
- [https://forum.djangoproject.com/t/support-nulls-not-distinct-
postgres-15-clause/21973/3 Recent thread on the subject in the forums]
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Ticket URL: <https://code.djangoproject.com/ticket/34701#comment:1>
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