Optimize ExpressionFieldPath

2 files changed, 4 insertions, 5 deletions

diff --git a/src/mongo/db/pipeline/expression.cpp b/src/mongo/db/pipeline/expression.cpp
index bf9586ad551..7e824c5d86d 100644
--- a/src/mongo/db/pipeline/expression.cpp
+++ b/src/mongo/db/pipeline/expression.cpp
@@ -1300,9 +1300,8 @@ namespace mongo {
     Value ExpressionFieldPath::evaluatePath(size_t index,
                                             size_t pathLength,
                                             Document pDocument) const {
-        Value pValue; /* the return value */
-
-        pValue = pDocument->getValue(fieldPath.getFieldName(index));
+        // return value
+        Value pValue = pDocument->getValue(fieldPath.getFieldName(index));
 
         /* if the field doesn't exist, quit with an undefined value */
         if (pValue.missing())
diff --git a/src/mongo/db/pipeline/field_path.h b/src/mongo/db/pipeline/field_path.h
index c3b9aa2a22c..4ff97817fbe 100755
--- a/src/mongo/db/pipeline/field_path.h
+++ b/src/mongo/db/pipeline/field_path.h
@@ -46,7 +46,7 @@ namespace mongo {
           @param i the zero based index of the path element.
           @returns the path element
          */
-        string getFieldName(size_t i) const;
+        const string& getFieldName(size_t i) const;
 
         /**
           Get the full path.
@@ -102,7 +102,7 @@ namespace mongo {
         return vFieldName.size();
     }
 
-    inline string FieldPath::getFieldName(size_t i) const {
+    inline const string& FieldPath::getFieldName(size_t i) const {
         verify(i < getPathLength());
         return vFieldName[i];
     }