SERVER-40755 Expose statistics which indicate how many collection scans have executed

1 files changed, 11 insertions, 2 deletions

diff --git a/src/mongo/db/catalog/collection_info_cache.h b/src/mongo/db/catalog/collection_info_cache.h
index 254df201721..8ae84fb3eec 100644
--- a/src/mongo/db/catalog/collection_info_cache.h
+++ b/src/mongo/db/catalog/collection_info_cache.h
@@ -31,6 +31,7 @@
 
 #include "mongo/db/collection_index_usage_tracker.h"
 #include "mongo/db/query/plan_cache.h"
+#include "mongo/db/query/plan_summary_stats.h"
 #include "mongo/db/query/query_settings.h"
 #include "mongo/db/update_index_data.h"
 
@@ -77,6 +78,12 @@ public:
     virtual CollectionIndexUsageMap getIndexUsageStats() const = 0;
 
     /**
+     * Returns a struct containing information on the number of collection scans that have been
+     * performed.
+     */
+    virtual CollectionIndexUsageTracker::CollectionScanStats getCollectionScanStats() const = 0;
+
+    /**
      * Register a newly-created index with the cache.  Must be called whenever an index is
      * built on the associated collection.
      *
@@ -99,10 +106,12 @@ public:
 
     /**
      * Signal to the cache that a query operation has completed.  'indexesUsed' should list the
-     * set of indexes used by the winning plan, if any.
+     * set of indexes used by the winning plan, if any. 'summaryStats.collectionScans' and
+     * 'summaryStats.collectionScansNonTailable' should be the number of collections scans and
+     * non-tailable collection scans that occured while executing the winning plan.
      */
     virtual void notifyOfQuery(OperationContext* const opCtx,
-                               const std::set<std::string>& indexesUsed) = 0;
+                               const PlanSummaryStats& summaryStats) = 0;
 
     virtual void setNs(NamespaceString ns) = 0;
 };