1 files changed, 11 insertions, 0 deletions
diff --git a/src/mongo/db/query/plan_ranker.h b/src/mongo/db/query/plan_ranker.h
index 1f0f1779b19..973429c0609 100644
--- a/src/mongo/db/query/plan_ranker.h
+++ b/src/mongo/db/query/plan_ranker.h
@@ -86,6 +86,9 @@ namespace mongo {
      * and used by the CachedPlanRunner to compare expected performance with actual.
      */
     struct PlanRankingDecision {
+
+        PlanRankingDecision() : tieForBest(false) { }
+
         /**
          * Make a deep copy.
          */
@@ -98,6 +101,7 @@ namespace mongo {
             }
             decision->scores = scores;
             decision->candidateOrder = candidateOrder;
+            decision->tieForBest = tieForBest;
             return decision;
         }
 
@@ -116,6 +120,13 @@ namespace mongo {
         // candidates[candidateOrder[1]] followed by
         // candidates[candidateOrder[2]], ...
         std::vector<size_t> candidateOrder;
+
+        // Did two plans tie for best?
+        //
+        // NOTE: Reading this is the only reliable way to determine if there was a tie,
+        // because the scores kept inside the PlanRankingDecision do not incorporate
+        // the EOF bonus.
+        bool tieForBest;
     };
 
 }  // namespace mongo