SERVER-48529 Delete PlanCache::feedback() and related code

3 files changed, 0 insertions, 53 deletions

diff --git a/src/mongo/db/query/plan_cache.cpp b/src/mongo/db/query/plan_cache.cpp
index f0c7e0384cd..5a8e140a3c5 100644
--- a/src/mongo/db/query/plan_cache.cpp
+++ b/src/mongo/db/query/plan_cache.cpp
@@ -240,7 +240,6 @@ std::unique_ptr<PlanCacheEntry> PlanCacheEntry::create(
         queryHash,
         planCacheKey,
         std::move(decision),
-        {},
         isActive,
         works));
 }
@@ -254,7 +253,6 @@ PlanCacheEntry::PlanCacheEntry(std::vector<std::unique_ptr<const SolutionCacheDa
                                const uint32_t queryHash,
                                const uint32_t planCacheKey,
                                std::unique_ptr<const PlanRankingDecision> decision,
-                               std::vector<double> feedback,
                                const bool isActive,
                                const size_t works)
     : plannerData(std::move(plannerData)),
@@ -266,7 +264,6 @@ PlanCacheEntry::PlanCacheEntry(std::vector<std::unique_ptr<const SolutionCacheDa
       queryHash(queryHash),
       planCacheKey(planCacheKey),
       decision(std::move(decision)),
-      feedback(std::move(feedback)),
       isActive(isActive),
       works(works),
       _entireObjectSize(_estimateObjectSizeInBytes()) {
@@ -296,7 +293,6 @@ std::unique_ptr<PlanCacheEntry> PlanCacheEntry::clone() const {
                                                               queryHash,
                                                               planCacheKey,
                                                               std::move(decisionPtr),
-                                                              feedback,
                                                               isActive,
                                                               works));
 }
@@ -307,8 +303,6 @@ uint64_t PlanCacheEntry::_estimateObjectSizeInBytes() const {
             plannerData,
             [](const auto& cacheData) { return cacheData->estimateObjectSizeInBytes(); },
             true) +
-        // Add size of each entry in '_feedback' vector.
-        container_size_helper::estimateObjectSizeInBytes(feedback) +
         // Add the entire size of 'decision' object.
         (decision ? decision->estimateObjectSizeInBytes() : 0) +
         // Add the size of all the owned BSON objects.
@@ -672,25 +666,6 @@ PlanCache::GetResult PlanCache::get(const PlanCacheKey& key) const {
     return {state, std::make_unique<CachedSolution>(key, *entry)};
 }
 
-Status PlanCache::feedback(const CanonicalQuery& cq, double score) {
-    PlanCacheKey ck = computeKey(cq);
-
-    stdx::lock_guard<Latch> cacheLock(_cacheMutex);
-    PlanCacheEntry* entry;
-    Status cacheStatus = _cache.get(ck, &entry);
-    if (!cacheStatus.isOK()) {
-        return cacheStatus;
-    }
-    invariant(entry);
-
-    // We store up to a constant number of feedback entries.
-    if (entry->feedback.size() < static_cast<size_t>(internalQueryCacheFeedbacksStored.load())) {
-        entry->feedback.push_back(score);
-    }
-
-    return Status::OK();
-}
-
 Status PlanCache::remove(const CanonicalQuery& canonicalQuery) {
     stdx::lock_guard<Latch> cacheLock(_cacheMutex);
     return _cache.remove(computeKey(canonicalQuery));
diff --git a/src/mongo/db/query/plan_cache.h b/src/mongo/db/query/plan_cache.h
index 4d448650808..c5d3133302d 100644
--- a/src/mongo/db/query/plan_cache.h
+++ b/src/mongo/db/query/plan_cache.h
@@ -365,9 +365,6 @@ public:
     // Information that went into picking the winning plan and also why the other plans lost.
     const std::unique_ptr<const PlanRankingDecision> decision;
 
-    // Scores from uses of this cache entry.
-    std::vector<double> feedback;
-
     // Whether or not the cache entry is active. Inactive cache entries should not be used for
     // planning.
     bool isActive = false;
@@ -396,7 +393,6 @@ private:
                    uint32_t queryHash,
                    uint32_t planCacheKey,
                    std::unique_ptr<const PlanRankingDecision> decision,
-                   std::vector<double> feedback,
                    bool isActive,
                    size_t works);
 
@@ -516,21 +512,6 @@ public:
      */
     std::unique_ptr<CachedSolution> getCacheEntryIfActive(const PlanCacheKey& key) const;
 
-
-    /**
-     * When the CachedPlanStage runs a plan out of the cache, we want to record data about the
-     * plan's performance. The CachedPlanStage calls feedback(...) after executing the cached
-     * plan for a trial period in order to do this. Currently, the only feedback metric recorded is
-     * the score associated with the cached plan trial period.
-     *
-     * If the entry corresponding to 'cq' isn't in the cache anymore, the feedback is ignored
-     * and an error Status is returned.
-     *
-     * If the entry corresponding to 'cq' still exists, 'feedback' is added to the run
-     * statistics about the plan.  Status::OK() is returned.
-     */
-    Status feedback(const CanonicalQuery& cq, double score);
-
     /**
      * Remove the entry corresponding to 'ck' from the cache.  Returns Status::OK() if the plan
      * was present and removed and an error status otherwise.
diff --git a/src/mongo/db/query/query_knobs.idl b/src/mongo/db/query/query_knobs.idl
index 644c5c0fab9..618e9aedd8d 100644
--- a/src/mongo/db/query/query_knobs.idl
+++ b/src/mongo/db/query/query_knobs.idl
@@ -98,15 +98,6 @@ server_parameters:
     validator:
       gte: 0
 
-  internalQueryCacheFeedbacksStored:
-    description: "How many feedback entries do we collect before possibly evicting from the cache based on bad performance?"
-    set_at: [ startup, runtime ]
-    cpp_varname: "internalQueryCacheFeedbacksStored"
-    cpp_vartype: AtomicWord<int>
-    default: 20
-    validator:
-      gte: 0
-
   internalQueryCacheEvictionRatio:
     description: "How many times more works must we perform in order to justify plan cache eviction and replanning?"
     set_at: [ startup, runtime ]