From 3e39c96ebbd90ebeb91d46f9dace6988a0152763 Mon Sep 17 00:00:00 2001
From: David Storch <david.storch@10gen.com>
Date: Tue, 3 Jun 2014 11:04:28 -0400
Subject: SERVER-14096 explain find() at queryPlanner verbosity

Enable by the setParameter 'enableNewExplain'
---
 src/mongo/db/exec/multi_plan.h | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

(limited to 'src/mongo/db/exec/multi_plan.h')

diff --git a/src/mongo/db/exec/multi_plan.h b/src/mongo/db/exec/multi_plan.h
index 359f3381198..fe25dcddfde 100644
--- a/src/mongo/db/exec/multi_plan.h
+++ b/src/mongo/db/exec/multi_plan.h
@@ -53,6 +53,11 @@ namespace mongo {
 
         virtual ~MultiPlanStage();
 
+        /**
+         * Helper used by the destructor to delete losing candidate plans.
+         */
+        void clearCandidates();
+
         virtual bool isEOF();
 
         virtual StageState work(WorkingSetID* out);
@@ -69,7 +74,7 @@ namespace mongo {
         void addPlan(QuerySolution* solution, PlanStage* root, WorkingSet* sharedWs);
 
         /**
-         * Runs all plans added by addPlan, ranks them, and picks a best.  Deletes all loser plans.
+         * Runs all plans added by addPlan, ranks them, and picks a best.
          * All further calls to getNext(...) will return results from the best plan.
          */
         void pickBestPlan();
@@ -90,6 +95,35 @@ namespace mongo {
          */
         bool hasBackupPlan() const;
 
+        /**
+         * Gathers execution stats for all losing plans.
+         */
+        vector<PlanStageStats*>* generateCandidateStats();
+
+        //
+        // Used by explain.
+        //
+
+        /**
+         * Runs the winning plan into it hits EOF or returns DEAD, throwing out the results.
+         * Execution stats are gathered in the process.
+         *
+         * You can call this after calling pickBestPlan(...). It expects that a winning plan
+         * has already been selected.
+         */
+        Status executeWinningPlan();
+
+        /**
+         * Runs the candidate plans until each has either hit EOF or returned DEAD. Results
+         * from the plans are thrown out, but execution stats are gathered.
+         *
+         * You can call this after calling pickBestPlan(...). It expects that a winning plan
+         * has already been selected.
+         */
+        Status executeAllPlans();
+
+        static const char* kStageType;
+
     private:
         //
         // Have all our candidate plans do something.
-- 
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