SERVER-16527 S2NearStage explain correctly reports nscanned, nscannedObjects, and isMultiKey

6 files changed, 67 insertions, 20 deletions

diff --git a/src/mongo/db/exec/index_scan.cpp b/src/mongo/db/exec/index_scan.cpp
index 062ba1b5162..2323b11102b 100644
--- a/src/mongo/db/exec/index_scan.cpp
+++ b/src/mongo/db/exec/index_scan.cpp
@@ -338,6 +338,14 @@ namespace mongo {
         }
     }
 
+    CommonStats* IndexScan::getCommonStats() {
+        return &_commonStats;
+    }
+
+    IndexScanStats* IndexScan::getSpecificStats() {
+        return &_specificStats;
+    }
+
     PlanStageStats* IndexScan::getStats() {
         // WARNING: this could be called even if the collection was dropped.  Do not access any
         // catalog information here.
diff --git a/src/mongo/db/exec/index_scan.h b/src/mongo/db/exec/index_scan.h
index 6d08f76b09a..d5bffbf7439 100644
--- a/src/mongo/db/exec/index_scan.h
+++ b/src/mongo/db/exec/index_scan.h
@@ -112,6 +112,16 @@ namespace mongo {
 
         virtual PlanStageStats* getStats();
 
+        /**
+         * Get an unowned pointer to this stage's common stats.
+         */
+        CommonStats* getCommonStats();
+
+        /**
+         * Get an unowned pointer to this stage's specific stats.
+         */
+        IndexScanStats* getSpecificStats();
+
     private:
         /**
          * Initialize the underlying IndexCursor, grab information from the catalog for stats.
diff --git a/src/mongo/db/exec/plan_stats.h b/src/mongo/db/exec/plan_stats.h
index 536b4d822ff..5266bf99491 100644
--- a/src/mongo/db/exec/plan_stats.h
+++ b/src/mongo/db/exec/plan_stats.h
@@ -349,6 +349,19 @@ namespace mongo {
         size_t forcedFetches;
     };
 
+    struct S2NearStats : public SpecificStats {
+        S2NearStats() : nscanned(0), nscannedObjects(0), isMultiKey(false) { }
+
+        virtual SpecificStats* clone() const {
+            S2NearStats* specific = new S2NearStats(*this);
+            return specific;
+        }
+
+        size_t nscanned;
+        size_t nscannedObjects;
+        bool isMultiKey;
+    };
+
     struct ShardingFilterStats : public SpecificStats {
         ShardingFilterStats() : chunkSkips(0) { }
 
diff --git a/src/mongo/db/exec/s2near.cpp b/src/mongo/db/exec/s2near.cpp
index 8ad0c2bd9eb..30770d4c22f 100644
--- a/src/mongo/db/exec/s2near.cpp
+++ b/src/mongo/db/exec/s2near.cpp
@@ -30,7 +30,6 @@
 
 #include "mongo/db/client.h"
 #include "mongo/db/catalog/database.h"
-#include "mongo/db/exec/fetch.h"
 #include "mongo/db/exec/index_scan.h"
 #include "mongo/db/exec/working_set_common.h"
 #include "mongo/db/exec/working_set_computed_data.h"
@@ -40,12 +39,13 @@
 
 namespace mongo {
 
-    S2NearStage::S2NearStage(const S2NearParams& params, WorkingSet* ws) {
-        _initted = false;
-        _params = params;
-        _ws = ws;
-        _worked = false;
-        _failed = false;
+    S2NearStage::S2NearStage(const S2NearParams& params, WorkingSet* ws)
+        : _worked(false),
+          _params(params),
+          _ws(ws),
+          _indexScan(NULL),
+          _failed(false),
+          _initted(false) {
     }
 
     void S2NearStage::init() {
@@ -278,10 +278,10 @@ namespace mongo {
         // Owns geo filter.
         _keyGeoFilter.reset(new GeoS2KeyMatchExpression(
             &_annulus, _params.baseBounds.fields[_nearFieldIndex].name));
-        IndexScan* scan = new IndexScan(params, _ws, _keyGeoFilter.get());
+        _indexScan = new IndexScan(params, _ws, _keyGeoFilter.get());
 
-        // Owns 'scan'.
-        _child.reset(new FetchStage(_ws, scan, _params.filter));
+        // Owns '_indexScan'.
+        _child.reset(new FetchStage(_ws, _indexScan, _params.filter));
         _seenInScan.clear();
     }
 
@@ -290,6 +290,15 @@ namespace mongo {
 
         // All done reading from _child.
         if (PlanStage::IS_EOF == state) {
+            // Aggregate stats from index scan used to get results for the annulus.
+            invariant(_indexScan);
+            _specificStats.nscanned += _indexScan->getSpecificStats()->keysExamined;
+            _specificStats.nscannedObjects += _indexScan->getCommonStats()->advanced;
+            if (_indexScan->getSpecificStats()->isMultiKey) {
+                _specificStats.isMultiKey = true;
+            }
+            _indexScan = NULL;
+
             _child.reset();
             _keyGeoFilter.reset();
 
@@ -426,10 +435,10 @@ namespace mongo {
     }
 
     PlanStageStats* S2NearStage::getStats() {
-        // TODO: must agg stats across child ixscan/fetches.
-        // TODO: we can do better than this, need own common stats.
         _commonStats.isEOF = isEOF();
-        return new PlanStageStats(_commonStats, STAGE_GEO_NEAR_2DSPHERE);
+        auto_ptr<PlanStageStats> ret(new PlanStageStats(_commonStats, STAGE_GEO_NEAR_2DSPHERE));
+        ret->specific.reset(new S2NearStats(_specificStats));
+        return ret.release();
     }
 
 }  // namespace mongo
diff --git a/src/mongo/db/exec/s2near.h b/src/mongo/db/exec/s2near.h
index 054b4cce16f..9f9c1d07354 100644
--- a/src/mongo/db/exec/s2near.h
+++ b/src/mongo/db/exec/s2near.h
@@ -30,6 +30,8 @@
 
 #include <queue>
 
+#include "mongo/db/exec/fetch.h"
+#include "mongo/db/exec/index_scan.h"
 #include "mongo/db/exec/plan_stage.h"
 #include "mongo/db/geo/geoquery.h"
 #include "mongo/db/geo/s2common.h"
@@ -94,7 +96,11 @@ namespace mongo {
         // Geo filter in index scan (which is owned by fetch stage in _child).
         scoped_ptr<MatchExpression> _keyGeoFilter;
 
-        scoped_ptr<PlanStage> _child;
+        // The child fetch stage for the current annulus.
+        scoped_ptr<FetchStage> _child;
+
+        // The child of '_child'. Not owned here.
+        IndexScan* _indexScan;
 
         // The S2 machinery that represents the search annulus.  We keep this around after bounds
         // generation to check for intersection.
@@ -153,6 +159,7 @@ namespace mongo {
         IndexDescriptor* _descriptor;
 
         CommonStats _commonStats;
+        S2NearStats _specificStats;
     };
 
 }  // namespace mongo
diff --git a/src/mongo/db/query/explain_plan.cpp b/src/mongo/db/query/explain_plan.cpp
index 750e770e14e..f9c24ecdee6 100644
--- a/src/mongo/db/query/explain_plan.cpp
+++ b/src/mongo/db/query/explain_plan.cpp
@@ -260,15 +260,15 @@ namespace mongo {
                 res->setIndexOnly(false);
             }
             else if (leaf->stageType == STAGE_GEO_NEAR_2DSPHERE) {
-                // TODO: This is kind of a lie for STAGE_GEO_NEAR_2DSPHERE.
+                S2NearStats* s2stats = static_cast<S2NearStats*>(leaf->specific.get());
                 res->setCursor("S2NearCursor");
-                // The first work() is an init.  Every subsequent work examines a document.
-                res->setNScanned(leaf->common.works);
-                res->setNScannedObjects(leaf->common.works);
+
+                res->setNScanned(s2stats->nscanned);
+                res->setNScannedObjects(s2stats->nscannedObjects);
+
                 // TODO: only adding empty index bounds for backwards compatibility.
                 res->setIndexBounds(BSONObj());
-                // TODO: Could be multikey.
-                res->setIsMultiKey(false);
+                res->setIsMultiKey(s2stats->isMultiKey);
                 res->setIndexOnly(false);
             }
             else if (leaf->stageType == STAGE_GEO_NEAR_2D) {