SERVER-33303 Add stable plan cache key and use for index filters

1 files changed, 12 insertions, 2 deletions

diff --git a/src/mongo/db/query/explain.cpp b/src/mongo/db/query/explain.cpp
index 95b07d91c68..92586ac1c47 100644
--- a/src/mongo/db/query/explain.cpp
+++ b/src/mongo/db/query/explain.cpp
@@ -45,6 +45,7 @@
 #include "mongo/db/exec/text.h"
 #include "mongo/db/exec/working_set_common.h"
 #include "mongo/db/keypattern.h"
+#include "mongo/db/query/canonical_query_encoder.h"
 #include "mongo/db/query/get_executor.h"
 #include "mongo/db/query/plan_executor.h"
 #include "mongo/db/query/plan_summary_stats.h"
@@ -645,13 +646,17 @@ void Explain::generatePlannerInfo(PlanExecutor* exec,
     // field will always be false in the case of EOF or idhack plans.
     bool indexFilterSet = false;
     boost::optional<uint32_t> queryHash;
+    boost::optional<uint32_t> planCacheKeyHash;
     if (collection && exec->getCanonicalQuery()) {
         const CollectionInfoCache* infoCache = collection->infoCache();
         const QuerySettings* querySettings = infoCache->getQuerySettings();
         PlanCacheKey planCacheKey =
             infoCache->getPlanCache()->computeKey(*exec->getCanonicalQuery());
-        queryHash = PlanCache::computeQueryHash(planCacheKey);
-        if (auto allowedIndicesFilter = querySettings->getAllowedIndicesFilter(planCacheKey)) {
+        planCacheKeyHash = canonical_query_encoder::computeHash(planCacheKey.toString());
+        queryHash = canonical_query_encoder::computeHash(planCacheKey.getStableKeyStringData());
+
+        if (auto allowedIndicesFilter =
+                querySettings->getAllowedIndicesFilter(planCacheKey.getStableKey())) {
             // Found an index filter set on the query shape.
             indexFilterSet = true;
         }
@@ -675,6 +680,10 @@ void Explain::generatePlannerInfo(PlanExecutor* exec,
         plannerBob.append("queryHash", unsignedIntToFixedLengthHex(*queryHash));
     }
 
+    if (planCacheKeyHash) {
+        plannerBob.append("planCacheKey", unsignedIntToFixedLengthHex(*planCacheKeyHash));
+    }
+
     BSONObjBuilder winningPlanBob(plannerBob.subobjStart("winningPlan"));
     const auto winnerStats = getWinningPlanStatsTree(exec);
     statsToBSON(*winnerStats.get(), &winningPlanBob, ExplainOptions::Verbosity::kQueryPlanner);
@@ -999,6 +1008,7 @@ void Explain::planCacheEntryToBSON(const PlanCacheEntry& entry, BSONObjBuilder*
     }
     shapeBuilder.doneFast();
     out->append("queryHash", unsignedIntToFixedLengthHex(entry.queryHash));
+    out->append("planCacheKey", unsignedIntToFixedLengthHex(entry.planCacheKey));
 
     // Append whether or not the entry is active.
     out->append("isActive", entry.isActive);