Refs #27030 -- Added index type introspection on PostgreSQL.

django/contrib/gis/db/backends/postgis/introspection.py

@@ -24,14 +24,16 @@ class PostGISIntrospection(DatabaseIntrospection):
     # expression over the raster column through the ST_ConvexHull function.
     # So the default query has to be adapted to include raster indices.
     _get_indexes_query = """
-        SELECT DISTINCT attr.attname, idx.indkey, idx.indisunique, idx.indisprimary
-        FROM pg_catalog.pg_class c, pg_catalog.pg_class c2,
-            pg_catalog.pg_index idx, pg_catalog.pg_attribute attr
-        LEFT JOIN pg_catalog.pg_type t ON t.oid = attr.atttypid
+        SELECT DISTINCT attr.attname, idx.indkey, idx.indisunique, idx.indisprimary,
+            am.amname
+        FROM pg_catalog.pg_class c, pg_catalog.pg_class c2, pg_catalog.pg_index idx,
+            pg_catalog.pg_attribute attr, pg_catalog.pg_type t, pg_catalog.pg_am am
         WHERE
             c.oid = idx.indrelid
             AND idx.indexrelid = c2.oid
             AND attr.attrelid = c.oid
+            AND t.oid = attr.atttypid
+            AND c2.relam = am.oid
             AND (
                 attr.attnum = idx.indkey[0] OR
                 (t.typname LIKE 'raster' AND idx.indkey = '0')

django/db/backends/base/features.py

@@ -163,6 +163,9 @@ class BaseDatabaseFeatures(object):
     # Can the backend introspect the column order (ASC/DESC) for indexes?
     supports_index_column_ordering = True
 
+    # Can the backend introspect the type of index created?
+    can_introspect_index_type = False
+
     # Support for the DISTINCT ON clause
     can_distinct_on_fields = False
 

django/db/backends/postgresql/features.py

@@ -22,6 +22,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     can_introspect_autofield = True
     can_introspect_ip_address_field = True
     can_introspect_small_integer_field = True
+    can_introspect_index_type = True
     can_distinct_on_fields = True
     can_rollback_ddl = True
     supports_combined_alters = True

django/db/backends/postgresql/introspection.py

@@ -36,13 +36,15 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
     ignored_tables = []
 
     _get_indexes_query = """
-        SELECT attr.attname, idx.indkey, idx.indisunique, idx.indisprimary
+        SELECT attr.attname, idx.indkey, idx.indisunique, idx.indisprimary,
+            am.amname
         FROM pg_catalog.pg_class c, pg_catalog.pg_class c2,
-            pg_catalog.pg_index idx, pg_catalog.pg_attribute attr
+            pg_catalog.pg_index idx, pg_catalog.pg_attribute attr, pg_catalog.pg_am am
         WHERE c.oid = idx.indrelid
             AND idx.indexrelid = c2.oid
             AND attr.attrelid = c.oid
             AND attr.attnum = idx.indkey[0]
+            AND c2.relam = am.oid
             AND c.relname = %s"""
 
     def get_field_type(self, data_type, description):
@@ -132,6 +134,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             # row[1] (idx.indkey) is stored in the DB as an array. It comes out as
             # a string of space-separated integers. This designates the field
             # indexes (1-based) of the fields that have indexes on the table.
+            # row[4] is the type of index, e.g. btree, hash, etc.
             # Here, we skip any indexes across multiple fields.
             if ' ' in row[1]:
                 continue
@@ -142,6 +145,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                 indexes[row[0]]['primary_key'] = True
             if row[2]:
                 indexes[row[0]]['unique'] = True
+            indexes[row[0]]['type'] = row[4]
         return indexes
 
     def get_constraints(self, cursor, table_name):

tests/introspection/tests.py

@@ -170,6 +170,11 @@ class IntrospectionTests(TransactionTestCase):
     def test_get_indexes(self):
         with connection.cursor() as cursor:
             indexes = connection.introspection.get_indexes(cursor, Article._meta.db_table)
+        if connection.features.can_introspect_index_type:
+            index_type = indexes['reporter_id'].pop('type', None)
+            self.assertIsNotNone(index_type)
+            if connection.vendor == 'postgresql':
+                self.assertEqual(index_type, 'btree')
         self.assertEqual(indexes['reporter_id'], {'unique': False, 'primary_key': False})
 
     def test_get_indexes_multicol(self):