enable DatabaseFeatures.supports_expression_indexes on CockroachDB 21.2+

README.md

@@ -95,7 +95,6 @@ using back to Cockroach Labs. To disable this, set
 
    - [changing column type if it's part of an index](https://go.crdb.dev/issue/47636)
    - dropping or changing a table's primary key
-   - [indexes on expressions](https://github.com/cockroachdb/cockroach/issues/9682) (Django's [`Index.expressions`](https://docs.djangoproject.com/en/stable/ref/models/indexes/#django.db.models.Index.expressions))
    - CockroachDB executes `ALTER COLUMN` queries asynchronously which is at
      odds with Django's assumption that the database is altered before the next
      migration operation begins. CockroachDB will give an error like
@@ -137,6 +136,12 @@ using back to Cockroach Labs. To disable this, set
        overlaps_below (&>|)](https://github.com/cockroachdb/cockroach/issues/57098)
      - [strictly_above (|>>), strictly_below (<<|)](https://github.com/cockroachdb/cockroach/issues/57095)
 
+## Known issues and limitations in CockroachDB 21.1.x and earlier
+
+- [Indexes on expressions](https://github.com/cockroachdb/cockroach/issues/9682)
+  (Django's [`Index.expressions`](https://docs.djangoproject.com/en/stable/ref/models/indexes/#django.db.models.Index.expressions))
+  aren't supported.
+
 ## Known issues and limitations in CockroachDB 20.2.x and earlier
 
 - Changing a column's type isn't supported.

django_cockroachdb/features.py

@@ -1,3 +1,5 @@
+import operator
+
 from django.db.backends.postgresql.features import (
     DatabaseFeatures as PostgresDatabaseFeatures,
 )
@@ -74,7 +76,7 @@ def introspected_field_types(self):
     }
 
     # Not supported: https://github.com/cockroachdb/cockroach/issues/9682
-    supports_expression_indexes = False
+    supports_expression_indexes = property(operator.attrgetter('is_cockroachdb_21_2'))
 
     @cached_property
     def is_cockroachdb_21_1(self):
@@ -184,9 +186,20 @@ def django_test_expected_failures(self):
             'model_fields.test_jsonfield.TestQuerying.test_order_grouping_custom_decoder',
             'model_fields.test_jsonfield.TestQuerying.test_ordering_by_transform',
             'model_fields.test_jsonfield.TestQuerying.test_ordering_grouping_by_key_transform',
+            # cannot index a json element:
+            # https://github.com/cockroachdb/cockroach/issues/30690
+            'schema.tests.SchemaTests.test_func_index_json_key_transform',
             # unexpected partial unique index in pg_constraint query:
             # https://github.com/cockroachdb/cockroach/issues/61098
             'introspection.tests.IntrospectionTests.test_get_constraints_unique_indexes_orders',
+            # COLLATE expressions in index elements not supported:
+            # https://github.com/cockroachdb/cockroach/issues/71240
+            'schema.tests.SchemaTests.test_func_index_collate',
+            'schema.tests.SchemaTests.test_func_index_collate_f_ordered',
+            # ALTER COLUMN ... SET NOT NULL crashes with "validate check
+            # constraint: column "crdb_internal_idx_expr" does not exist":
+            # https://github.com/cockroachdb/cockroach/issues/72012
+            'migrations.test_operations.OperationTests.test_alter_field_with_func_index',
         })
         if not self.connection.features.is_cockroachdb_21_1:
             expected_failures.update({