merge: DOCS-734

Author: Sam Kleinman

source/reference/glossary.txt

@@ -463,11 +463,19 @@ Glossary
       management.
 
    natural order
-      The order in which a database stores documents on disk.
-      Typically this order is the same as the
-      insertion order. :term:`Capped collections <capped collection>`,
-      among other things, guarantee that insertion order and natural
-      order are identical.
+      The order in which a database stores documents on
+      disk. Typically, the order of documents on disks reflects
+      insertion order, *except* when documents move internal because
+      of document growth due to update operations. However,
+      :term:`Capped collections <capped collection>` guarantee that
+      insertion order and natural order are identical.
+
+      When you execute :method:`find() <db.collection.find()>` with no
+      parameters, the database returns documents in forward natural
+      order. When you execute :method:`find() <db.collection.find()>`
+      and include :method:`sort() <cursor.sort()>` with a parameter of
+      ``$natural:-1``, the database returns documents in reverse natural
+      order.
 
    primary key
       A record's unique, immutable identifier. In an :term:`RDBMS`, the primary

source/reference/method/cursor.sort.txt

@@ -47,3 +47,15 @@ cursor.sort()
       than 32 megabytes, MongoDB will return an error. Use
       :method:`cursor.limit()`, or create an index on the field that you're
       sorting to avoid this error.
+
+   The :operator:`$natural` parameter returns items according to their
+   order on disk. Consider the following query: 
+
+   .. code-block:: javascript
+
+      db.collection.find().sort( { $natural: -1 } )
+
+   This will return documents in the reverse of the order on
+   disk. Typically, the order of documents on disks reflects insertion
+   order, *except* when documents move internal because of document
+   growth due to update operations.