From 743d28f5539b17d6e39bd37c6e3df5628b470cac Mon Sep 17 00:00:00 2001
From: Nick Pope <nick.pope@flightdataservices.com>
Date: Tue, 5 Dec 2017 09:19:52 +0000
Subject: [PATCH] Refs #27869 -- Added PostgreSQL version check for GinIndex
 support.

---
 django/contrib/postgres/indexes.py   |  4 ++++
 tests/postgres_tests/test_indexes.py | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/django/contrib/postgres/indexes.py b/django/contrib/postgres/indexes.py
index 1850b209786..f8014f87a01 100644
--- a/django/contrib/postgres/indexes.py
+++ b/django/contrib/postgres/indexes.py
@@ -105,6 +105,10 @@ class GinIndex(PostgresIndex):
             kwargs['gin_pending_list_limit'] = self.gin_pending_list_limit
         return path, args, kwargs
 
+    def check_supported(self, schema_editor):
+        if self.gin_pending_list_limit and not schema_editor.connection.features.has_gin_pending_list_limit:
+            raise NotSupportedError('GIN option gin_pending_list_limit requires PostgreSQL 9.5+.')
+
     def get_with_params(self):
         with_params = []
         if self.gin_pending_list_limit is not None:
diff --git a/tests/postgres_tests/test_indexes.py b/tests/postgres_tests/test_indexes.py
index f4ac359a3ac..b9820aa362c 100644
--- a/tests/postgres_tests/test_indexes.py
+++ b/tests/postgres_tests/test_indexes.py
@@ -185,6 +185,16 @@ class SchemaTests(PostgreSQLTestCase):
             editor.remove_index(IntegerArrayModel, index)
         self.assertNotIn(index_name, self.get_constraints(IntegerArrayModel._meta.db_table))
 
+    def test_gin_parameters_exception(self):
+        index_name = 'gin_options_exception'
+        index = GinIndex(fields=['field'], name=index_name, gin_pending_list_limit=64)
+        msg = 'GIN option gin_pending_list_limit requires PostgreSQL 9.5+.'
+        with self.assertRaisesMessage(NotSupportedError, msg):
+            with mock.patch('django.db.connection.features.has_gin_pending_list_limit', False):
+                with connection.schema_editor() as editor:
+                    editor.add_index(IntegerArrayModel, index)
+        self.assertNotIn(index_name, self.get_constraints(IntegerArrayModel._meta.db_table))
+
     @skipUnlessDBFeature('has_brin_index_support')
     def test_brin_index(self):
         index_name = 'char_field_model_field_brin'