id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
25180	ArrayFields should not have varchar_patterns_ops or text_patterns_ops indexes	Fabian Büchler	Caio Ariede	"I believe I bumped into a bug using the new PostgreSQL `ArrayField` from 1.8 in combination with `db_index=True`:


This seems to be related to Django ticket #12234 which introduced creating secondary
`varchar_patterns_ops` or `text_patterns_ops` indexes for varchar or text fields
respectively, so that PostgreSQL could use them for the `contains` filter
(e.g. `MyModel.object.filter(name__contains='abc')`).

However, for the array fields introduced with Django 1.8 this does not seem to
work when having `db_index` activated. When `syncdb` or `migrate` try to
create the secondary index, PostgreSQL raises an error like this:

{{{#!python
django.db.utils.ProgrammingError: operator class ""varchar_pattern_ops"" does not accept data type character varying[]
}}}

The executed SQL statement is something like this:

{{{#!sql
CREATE INDEX ""shop_product_package_product_numbers_2ebd72fe1541fbd4_like"" ON ""shop_product"" (""package_product_numbers"" varchar_pattern_ops)
}}}

The important parts of the model defintion are:

{{{#!python
class Product(models.Model):

    package_product_numbers = ArrayField(
        models.CharField(max_length=10, blank=True),
        verbose_name=""Package product numbers"",
        null=True, default=None, db_index=True)
}}}

I'm currently using a workaroud to fix this. I created a custom DB backend that inherits from the postgresql_psycopg2 one and overwrites the `DatabaseCreation.sql_indexes_for_field` and `DatabaseSchemaEditor._model_indexes_sql` methods to check for ArrayFields when creating those secondary indexes. I can post this code here, if you need it, however, I don't think that this is the right solution, since the PostgreSQL database backend should not really need to know anything about the `django.contrib.postgresql` stuff.

Please let me know if I can help to reproduce this.
"	Bug	closed	contrib.postgres	1.8	Normal	fixed			Ready for checkin	1	0	0	0	0	0