Django Support for PostgreSQL 15+ NULLS NOT DISTINCT

Django 5.0 already supports the PostgreSQL 15+ NULLS NOT DISTINCT feature through the nulls_distinct attribute on the UniqueConstraint class.

How to Use It

You can create a unique constraint that treats NULL values as equivalent (not distinct) by setting nulls_distinct=False:

PYTHONCopied
from django.db import models

class MyModel(models.Model):
    name = models.CharField(max_length=100)
    ordering = models.IntegerField(null=True)

    class Meta:
        constraints = [
            models.UniqueConstraint(
                name="ordering_unique", 
                fields=["ordering"], 
                nulls_distinct=False
            )
        ]

In this example, the constraint only allows one row to store a NULL value in the ordering column, treating all NULL values as equivalent rather than distinct.

Important Notes

• This feature was introduced in Django 5.0
• It only works with PostgreSQL 15 and later
• For other database backends, unique constraints with nulls_distinct are ignored
• The default value is None, which uses the database default (which is True on most backends, meaning NULL values are treated as distinct)

This implementation gives you control over how NULL values are treated in unique constraints, matching the behavior introduced in PostgreSQL 15.