DOCSP-9558 added note about stable sorts

Author: ksadoff

source/fundamentals/crud/read/limit.txt

@@ -110,6 +110,29 @@ longest books:
 You can combine ``skip()`` and ``limit()`` in this way to implement paging for your
 collection, returning only small subsets of the collection at one time.
 
+.. note::
+
+  In order to ensure stable sorts across multiple queries, you must sort
+  using a unique key (such as ``_id``). Otherwise, a call to ``skip()``
+  and ``limit()`` may produce unpredictable results when combined with
+  ``sort()``.
+
+  For example, consider the following data:
+
+  .. code_block:: java
+      
+      { type: "computer", data: "1", serial_no: 235235 }
+      { type: "computer", data: "2", serial_no: 235237 }
+      { type: "computer", data: "3", serial_no: 235239 }
+      { type: "computer", data: "4", serial_no: 235241 }
+
+  If you sorted by ``type`` alone, ``sort()`` does not guarantee the same order
+  upon return. Appending ``skip()`` and ``limit()`` to the ``sort()``
+  could return different documents for different queries. In this case, sorting
+  by ``data`` or ``serial_no`` would guarantee a stable sort, as both are unique keys.
+
+
+
 For additional information on the classes and methods mentioned on this
 page, see the following API documentation: