Allow specifying custom operator classes for PostgreSQL indexes

[IzyJeepee]

Hello,

I want use the GinIndex method to create a gin index with the django's migration. But while the migration, I have this errror :

django.db.utils.ProgrammingError : data type character varying has no default operator class for access method "gin"
HINT : You must specify an operator class ofr the index or define a default operator class for the data type.

This error may be resolved by enabling the btree_gin extension.

It is possible to pass the operator class during the index's creation ? For example :

class Meta:
    indexes = [
        GinIndex(fields=['my_field'], name='my_index_gin', operator_class='my_operator')
    ]

Thanks

[Mads Jensen]

#27437 looks like it's overlapping a little bit.

[Tim Graham]

I don't have much expertise here about the use cases and how this might interact with #27437. Tentatively accepting for further investigation.

[Mads Jensen]

​https://github.com/mjtamlyn/django/blob/5ae3c70b405486fb81bcbf33b209f1301fade246/django/db/backends/postgresql/schema.py#L31-L35 so the issue of this may already being worked on?

[vinay karanam]

I've a use case where I am always doing __contains query on JSONField. So, I would prefer GIN index to be created using jsonb_path_ops operator class rather than the default jsonb_ops.

[Tim Graham]

#28783 was a duplicate and provides a ​PR.

[Ian Foote]

​Updated PR

[Ian Foote]

I've noticed that in the ​postgis schema editor, we have custom index creation code for single-field indexes for geodetic fields. For example, we set the GIST_GEOMETRY_OPS_ND operator class for fields with dimension higher than two.

It would probably be good to refactor to allow this custom code to integrate with the operator class support I've added, but I'm not familiar enough with postgis to be confident making a change without guidance.

[Tim Graham <timograham@…>]

In 38cada7:

Fixed #28077 -- Added support for PostgreSQL opclasses in Index.

Thanks Vinay Karanam for the initial patch.

[GitHub <noreply@…>]

In 82da72b:

Refs #28077 -- Added opclasses to Index.repr().

This also removes unnecessary commas between attributes.