[1.11.x] Fixed #27135 -- Made index introspection return Index.suffix.

Backport of b008f7cc5655d01817a8825e6317877b43c92181 from master

4 files changed, 7 insertions, 4 deletions

diff --git a/django/db/backends/mysql/introspection.py b/django/db/backends/mysql/introspection.py
index 457c8b7f48..b429e6a3cf 100644
--- a/django/db/backends/mysql/introspection.py
+++ b/django/db/backends/mysql/introspection.py
@@ -6,6 +6,7 @@ from MySQLdb.constants import FIELD_TYPE
 from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo, TableInfo,
 )
+from django.db.models.indexes import Index
 from django.utils.datastructures import OrderedSet
 from django.utils.deprecation import RemovedInDjango21Warning
 from django.utils.encoding import force_text
@@ -217,7 +218,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                     'foreign_key': None,
                 }
             constraints[index]['index'] = True
-            constraints[index]['type'] = type_.lower()
+            constraints[index]['type'] = Index.suffix if type_ == 'BTREE' else type_.lower()
             constraints[index]['columns'].add(column)
         # Convert the sorted sets to lists
         for constraint in constraints.values():
diff --git a/django/db/backends/oracle/introspection.py b/django/db/backends/oracle/introspection.py
index 7af2a18a8d..2d04fdac56 100644
--- a/django/db/backends/oracle/introspection.py
+++ b/django/db/backends/oracle/introspection.py
@@ -281,7 +281,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                     "foreign_key": None,
                     "check": False,
                     "index": True,
-                    "type": 'btree' if type_ == 'normal' else type_,
+                    "type": 'idx' if type_ == 'normal' else type_,
                 }
             # Record the details
             constraints[constraint]['columns'].append(column)
diff --git a/django/db/backends/postgresql/introspection.py b/django/db/backends/postgresql/introspection.py
index e9d7d0225f..c75f06f873 100644
--- a/django/db/backends/postgresql/introspection.py
+++ b/django/db/backends/postgresql/introspection.py
@@ -5,6 +5,7 @@ import warnings
 from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo, TableInfo,
 )
+from django.db.models.indexes import Index
 from django.utils.deprecation import RemovedInDjango21Warning
 from django.utils.encoding import force_text
 
@@ -236,7 +237,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                     "foreign_key": None,
                     "check": False,
                     "index": True,
-                    "type": type_,
+                    "type": Index.suffix if type_ == 'btree' else type_,
                     "definition": definition,
                     "options": options,
                 }
diff --git a/django/db/backends/sqlite3/introspection.py b/django/db/backends/sqlite3/introspection.py
index 7d24ca6f26..637a6a5332 100644
--- a/django/db/backends/sqlite3/introspection.py
+++ b/django/db/backends/sqlite3/introspection.py
@@ -4,6 +4,7 @@ import warnings
 from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo, TableInfo,
 )
+from django.db.models.indexes import Index
 from django.utils.deprecation import RemovedInDjango21Warning
 
 field_size_re = re.compile(r'^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$')
@@ -262,7 +263,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             # Add type and column orders for indexes
             if constraints[index]['index'] and not constraints[index]['unique']:
                 # SQLite doesn't support any index type other than b-tree
-                constraints[index]['type'] = 'btree'
+                constraints[index]['type'] = Index.suffix
                 cursor.execute(
                     "SELECT sql FROM sqlite_master "
                     "WHERE type='index' AND name=%s" % self.connection.ops.quote_name(index)