1 files changed, 16 insertions, 1 deletions
diff --git a/src/mongo/db/exec/multi_plan.h b/src/mongo/db/exec/multi_plan.h
index 14d8ea413af..12ab61659db 100644
--- a/src/mongo/db/exec/multi_plan.h
+++ b/src/mongo/db/exec/multi_plan.h
@@ -75,7 +75,6 @@ public:
 
     std::unique_ptr<PlanStageStats> getStats() final;
 
-
     const SpecificStats* getSpecificStats() const final;
 
     boost::optional<double> getCandidateScore(size_t candidateIdx) const;
@@ -163,6 +162,19 @@ private:
      */
     void tryYield(PlanYieldPolicy* yieldPolicy);
 
+    /**
+     * Deletes all children, except for best and backup plans.
+     *
+     * This is necessary to release any resources that rejected plans might have.
+     * For example, if multi-update can be done by scanning several indexes,
+     * it will be slowed down by rejected index scans because of index cursors
+     * that need to be reopeneed after every update.
+     */
+    void removeRejectedPlans();
+    void rejectPlan(size_t planIdx);
+    void switchToBackupPlan();
+    void removeBackupPlan();
+
     static const int kNoSuchPlan = -1;
 
     // Describes the cases in which we should write an entry for the winning plan to the plan cache.
@@ -178,6 +190,9 @@ private:
     // one-to-one with _candidates.
     std::vector<plan_ranker::CandidatePlan> _candidates;
 
+    // Rejected plans in saved and detached state.
+    std::vector<std::unique_ptr<PlanStage>> _rejected;
+
     // index into _candidates, of the winner of the plan competition
     // uses -1 / kNoSuchPlan when best plan is not (yet) known
     int _bestPlanIdx;