From d450986084b06a310c4d7182ef33d9fd80ebe255 Mon Sep 17 00:00:00 2001
From: Allison Moore <allison.moore@10gen.com>
Date: Thu, 15 Jan 2015 10:45:25 -0500
Subject: [PATCH] aggregation $sort clarification

- Clarifies that $sort cannot use the index if $group, $unwind, or
  $project occur before $sort.
---
 source/reference/operator/aggregation/sort.txt | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/source/reference/operator/aggregation/sort.txt b/source/reference/operator/aggregation/sort.txt
index ba0cdcd72e5..bcf983a8b8c 100644
--- a/source/reference/operator/aggregation/sort.txt
+++ b/source/reference/operator/aggregation/sort.txt
@@ -117,8 +117,11 @@ option in :method:`db.collection.aggregate()` method and the
 
 :pipeline:`$sort` operator can take advantage of an index when
 placed at the **beginning** of the pipeline or placed **before**
-the following aggregation operators: :pipeline:`$project`,
-:pipeline:`$unwind`, and :pipeline:`$group`.
-
+the :pipeline:`$project`,
+:pipeline:`$unwind`, and :pipeline:`$group` aggregation operators.
+If :pipeline:`$project`, :pipeline:`$unwind`, or :pipeline:`$group`
+occur prior to the :pipeline:`$sort` operation, :pipeline:`$sort` 
+cannot use any indexes.
+          
 .. todo:: if a sort precedes the first $group in a sharded system,
    all documents must go to the mongos for sorting.