#32932: Unique indexes
-------------------------------------+-------------------------------------
Reporter: David | Owner: nobody
Sanders |
Type: New | Status: new
feature |
Component: Database | Version: 3.2
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Django already supports both unique constraints and indexes from the
models Meta <3
A worthwhile addition would be to support _unique indexes_, if the
database makes this distinction.
In Postgres a unique index is a distinct feature from unique constraints;
unique indexes are the mechanism that enforces the unique constraints
declared for the table: https://www.postgresql.org/docs/current/indexes-
unique.html.
One important difference between the 2 is the fact that indexes may
support expressions whereas constraints do not (at least in PG).
An example may be to enforce a unique attribute in a jsonb field:
{{{
CREATE UNIQUE INDEX unique_attr ON some_table (
(some_json_field->>'some_attr') )
}}}
This could perhaps be a new option on the `Index` class:
{{{
class SomeTable(models.Model):
some_json_field = models.JSONField()
class Meta:
indexes = (
models.Index(models.RawSQL("some_json_field->>'some_attr'",
params=[]), name="unique_attr", unique=True),
)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/32932>
Django <https://code.djangoproject.com/>
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