diff --git a/bin/addons/base/ir/ir_attachment.py b/bin/addons/base/ir/ir_attachment.py
index 121b6a3de37..abba9222d25 100644
--- a/bin/addons/base/ir/ir_attachment.py
+++ b/bin/addons/base/ir/ir_attachment.py
@@ -124,6 +124,13 @@ class ir_attachment(osv.osv):
         'type': 'binary',
     }
 
+    def _auto_init(self, cr, context=None):
+        super(ir_attachment, self)._auto_init(cr, context)
+        cr.execute('SELECT indexname FROM pg_indexes WHERE indexname = %s', ('ir_attachment_res_idx',))
+        if not cr.fetchone():
+            cr.execute('CREATE INDEX ir_attachment_res_idx ON ir_attachment (res_model, res_id)')
+            cr.commit()
+
 ir_attachment()