Can't create GinIndex on ArrayField(CITextField)

[Davide Setti]

I have a model like:

class MyModel(models.Model):
    column = ArrayField(
        CITextField(max_length=255),
    )

    class Meta:
        indexes = [
            GinIndex(fields=['column'], name='mygin')
        ]

Migration fails because:

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

full trace on this ​gist. To solve this issue an Operator Class ​must be created

[Mads Jensen]

I have some code, tests, and documentation for this, although the SQL code from Stackoverflow appears to be incorrect (I get django.db.utils.InternalError: ginqueryarrayextract: unknown strategy number: 7).

[Mads Jensen]

​PR

[Simon Charette]

As I mentioned to the reporter at DUTH I'm not convinced this a common enough use case to ship and maintain a custom operation class. The fact that the citext extension doesn't ship with these operator classes itself makes be doubt it's commonly used.

I'd be in favor of moving the ticket to Someday/Maybe and see if this gather any traction as both GINIndex and CITextField are new features in the still unreleased Django 1.11.

[Mads Jensen]

I'm a bit indifferent to how this will get treated.

[Tim Graham]

Yes, this looks a bit specialized. In my opinion, contrib.postgres should aim for implementing things that are an ~80% use case. As Simon said, it would be nice to have more evidence that this is common before committing to include it. Anyway, the code is on the pull request for anyone who would like to use it in their own project.

[Mariusz Felisiak]

It's niche. Moreover the citext extension ​is ​discouraged since PostgreSQL 12 in favor of ​non-deterministic collations that are supported in Django 3.2+ via the new db_collation argument for CharField and TextField (see #31777).