SERVER-66935 Invalidate $lookup plan cache when foreign collection size changes

14 files changed, 125 insertions, 64 deletions

diff --git a/src/mongo/db/exec/plan_cache_util.cpp b/src/mongo/db/exec/plan_cache_util.cpp
index 1bd6f9fe75d..34e819890f4 100644
--- a/src/mongo/db/exec/plan_cache_util.cpp
+++ b/src/mongo/db/exec/plan_cache_util.cpp
@@ -176,7 +176,7 @@ plan_cache_debug_info::DebugInfoSBE buildDebugInfo(const QuerySolution* solution
             }
             case STAGE_EQ_LOOKUP: {
                 auto eln = static_cast<const EqLookupNode*>(node);
-                auto& secondaryStats = debugInfo.secondaryStats[eln->foreignCollection];
+                auto& secondaryStats = debugInfo.secondaryStats[eln->foreignCollection.toString()];
                 if (eln->lookupStrategy == EqLookupNode::LookupStrategy::kIndexedLoopJoin) {
                     tassert(6466200, "Index join lookup should have an index entry", eln->idxEntry);
                     secondaryStats.indexesUsed.push_back(eln->idxEntry->identifier.catalogName);
diff --git a/src/mongo/db/query/get_executor.cpp b/src/mongo/db/query/get_executor.cpp
index ae3c0d20c5f..c6a54e26102 100644
--- a/src/mongo/db/query/get_executor.cpp
+++ b/src/mongo/db/query/get_executor.cpp
@@ -1247,7 +1247,8 @@ std::unique_ptr<sbe::RuntimePlanner> makeRuntimePlannerIfNeeded(
     boost::optional<size_t> decisionWorks,
     bool needsSubplanning,
     PlanYieldPolicySBE* yieldPolicy,
-    size_t plannerOptions) {
+    size_t plannerOptions,
+    const stage_builder::PlanStageData& planStageData) {
     // If we have multiple solutions, we always need to do the runtime planning.
     if (numSolutions > 1) {
         invariant(!needsSubplanning && !decisionWorks);
@@ -1279,15 +1280,15 @@ std::unique_ptr<sbe::RuntimePlanner> makeRuntimePlannerIfNeeded(
 
     invariant(numSolutions == 1);
 
-    // If we have a single solution but it was created from a cached plan, we will need to do the
-    // runtime planning to check if the cached plan still performs efficiently, or requires
-    // re-planning. The 'decisionWorks' is used to determine whether the existing cache entry should
-    // be evicted, and the query re-planned.
-    if (decisionWorks) {
+    // If we have a single solution and the plan is not pinned or plan contains a hash_lookup stage,
+    // we will need we will need to do the runtime planning to check if the cached plan still
+    // performs efficiently, or requires re-planning.
+    const bool hasHashLookup = !planStageData.foreignHashJoinCollections.empty();
+    if (decisionWorks || hasHashLookup) {
         QueryPlannerParams plannerParams;
         plannerParams.options = plannerOptions;
         return std::make_unique<sbe::CachedSolutionPlanner>(
-            opCtx, collections, *canonicalQuery, plannerParams, *decisionWorks, yieldPolicy);
+            opCtx, collections, *canonicalQuery, plannerParams, decisionWorks, yieldPolicy);
     }
 
     // Runtime planning is not required.
@@ -1344,7 +1345,8 @@ StatusWith<std::unique_ptr<PlanExecutor, PlanExecutor::Deleter>> getSlotBasedExe
                                                   planningResult->decisionWorks(),
                                                   planningResult->needsSubplanning(),
                                                   yieldPolicy.get(),
-                                                  plannerParams.options)) {
+                                                  plannerParams.options,
+                                                  roots[0].second)) {
         // Do the runtime planning and pick the best candidate plan.
         auto candidates = planner->plan(std::move(solutions), std::move(roots));
 
diff --git a/src/mongo/db/query/plan_explainer_sbe.cpp b/src/mongo/db/query/plan_explainer_sbe.cpp
index 05e9e472fcb..fea5b81cea4 100644
--- a/src/mongo/db/query/plan_explainer_sbe.cpp
+++ b/src/mongo/db/query/plan_explainer_sbe.cpp
@@ -172,7 +172,7 @@ void statsToBSON(const QuerySolutionNode* node,
         case STAGE_EQ_LOOKUP: {
             auto eln = static_cast<const EqLookupNode*>(node);
 
-            bob->append("foreignCollection", eln->foreignCollection);
+            bob->append("foreignCollection", eln->foreignCollection.toString());
             bob->append("localField", eln->joinFieldLocal.fullPath());
             bob->append("foreignField", eln->joinFieldForeign.fullPath());
             bob->append("asField", eln->joinField.fullPath());
diff --git a/src/mongo/db/query/planner_analysis.cpp b/src/mongo/db/query/planner_analysis.cpp
index ce58c70ab64..d5e8f0acc28 100644
--- a/src/mongo/db/query/planner_analysis.cpp
+++ b/src/mongo/db/query/planner_analysis.cpp
@@ -644,18 +644,6 @@ void removeInclusionProjectionBelowGroupRecursive(QuerySolutionNode* solnRoot) {
     }
 }
 
-// Checks if the foreign collection is eligible for the hash join algorithm. We conservatively
-// choose the hash join algorithm for cases when the hash table is unlikely to spill data.
-bool isEligibleForHashJoin(const SecondaryCollectionInfo& foreignCollInfo) {
-    return !internalQueryDisableLookupExecutionUsingHashJoin.load() && foreignCollInfo.exists &&
-        foreignCollInfo.noOfRecords <=
-        internalQueryCollectionMaxNoOfDocumentsToChooseHashJoin.load() &&
-        foreignCollInfo.approximateDataSizeBytes <=
-        internalQueryCollectionMaxDataSizeBytesToChooseHashJoin.load() &&
-        foreignCollInfo.storageSizeBytes <=
-        internalQueryCollectionMaxStorageSizeBytesToChooseHashJoin.load();
-}
-
 // Determines whether 'index' is eligible for executing the right side of a pushed down $lookup over
 // 'foreignField'.
 bool isIndexEligibleForRightSideOfLookupPushdown(const IndexEntry& index,
@@ -667,6 +655,16 @@ bool isIndexEligibleForRightSideOfLookupPushdown(const IndexEntry& index,
 }
 }  // namespace
 
+bool QueryPlannerAnalysis::isEligibleForHashJoin(const SecondaryCollectionInfo& foreignCollInfo) {
+    return !internalQueryDisableLookupExecutionUsingHashJoin.load() && foreignCollInfo.exists &&
+        foreignCollInfo.noOfRecords <=
+        internalQueryCollectionMaxNoOfDocumentsToChooseHashJoin.load() &&
+        foreignCollInfo.approximateDataSizeBytes <=
+        internalQueryCollectionMaxDataSizeBytesToChooseHashJoin.load() &&
+        foreignCollInfo.storageSizeBytes <=
+        internalQueryCollectionMaxStorageSizeBytesToChooseHashJoin.load();
+}
+
 // static
 std::unique_ptr<QuerySolution> QueryPlannerAnalysis::removeInclusionProjectionBelowGroup(
     std::unique_ptr<QuerySolution> soln) {
diff --git a/src/mongo/db/query/planner_analysis.h b/src/mongo/db/query/planner_analysis.h
index 7ba6e8feeca..3233ef82d7b 100644
--- a/src/mongo/db/query/planner_analysis.h
+++ b/src/mongo/db/query/planner_analysis.h
@@ -147,6 +147,12 @@ public:
         const std::map<NamespaceString, SecondaryCollectionInfo>& collectionsInfo,
         bool allowDiskUse,
         const CollatorInterface* collator);
+
+    /**
+     * Checks if the foreign collection is eligible for the hash join algorithm. We conservatively
+     * choose the hash join algorithm for cases when the hash table is unlikely to spill to disk.
+     */
+    static bool isEligibleForHashJoin(const SecondaryCollectionInfo& foreignCollInfo);
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/query/query_planner.cpp b/src/mongo/db/query/query_planner.cpp
index 5ec4c27f84a..b7df376979a 100644
--- a/src/mongo/db/query/query_planner.cpp
+++ b/src/mongo/db/query/query_planner.cpp
@@ -1412,7 +1412,7 @@ std::unique_ptr<QuerySolution> QueryPlanner::extendWithAggPipeline(
                 query.getCollator());
             auto eqLookupNode =
                 std::make_unique<EqLookupNode>(std::move(solnForAgg),
-                                               lookupStage->getFromNs().toString(),
+                                               lookupStage->getFromNs(),
                                                lookupStage->getLocalField()->fullPath(),
                                                lookupStage->getForeignField()->fullPath(),
                                                lookupStage->getAsField().fullPath(),
diff --git a/src/mongo/db/query/query_planner_test_lib.cpp b/src/mongo/db/query/query_planner_test_lib.cpp
index e3e045a721c..ce1754ba817 100644
--- a/src/mongo/db/query/query_planner_test_lib.cpp
+++ b/src/mongo/db/query/query_planner_test_lib.cpp
@@ -1395,7 +1395,7 @@ Status QueryPlannerTestLib::solutionMatches(const BSONObj& testSoln,
                                   << testSoln.toString()};
         }
 
-        if (expectedForeignCollection.str() != actualEqLookupNode->foreignCollection) {
+        if (expectedForeignCollection.str() != actualEqLookupNode->foreignCollection.toString()) {
             return {
                 ErrorCodes::Error{6267502},
                 str::stream() << "Test solution 'foreignCollection' does not match actual; test "
diff --git a/src/mongo/db/query/query_solution.h b/src/mongo/db/query/query_solution.h
index 0965d1cd507..5f379bc5b05 100644
--- a/src/mongo/db/query/query_solution.h
+++ b/src/mongo/db/query/query_solution.h
@@ -1479,7 +1479,7 @@ struct EqLookupNode : public QuerySolutionNode {
     }
 
     EqLookupNode(std::unique_ptr<QuerySolutionNode> child,
-                 const std::string& foreignCollection,
+                 const NamespaceString& foreignCollection,
                  const FieldPath& joinFieldLocal,
                  const FieldPath& joinFieldForeign,
                  const FieldPath& joinField,
@@ -1528,9 +1528,9 @@ struct EqLookupNode : public QuerySolutionNode {
     std::unique_ptr<QuerySolutionNode> clone() const final;
 
     /**
-     * The foreign (inner) collection namespace name.
+     * The foreign (inner) collection namespace string.
      */
-    std::string foreignCollection;
+    NamespaceString foreignCollection;
 
     /**
      * The local (outer) join field.
diff --git a/src/mongo/db/query/query_solution_test.cpp b/src/mongo/db/query/query_solution_test.cpp
index 55003d3f8c1..522c2e108b9 100644
--- a/src/mongo/db/query/query_solution_test.cpp
+++ b/src/mongo/db/query/query_solution_test.cpp
@@ -1134,7 +1134,7 @@ TEST(QuerySolutionTest, EqLookupNodeWithIndexScan) {
     scanNode->bounds.endKey = BSON("a" << 1 << "b" << 1);
 
     EqLookupNode node(std::move(scanNode),
-                      "col",
+                      NamespaceString("db.col"),
                       "local",
                       "foreign",
                       "as",
@@ -1169,7 +1169,7 @@ TEST(QuerySolutionTest, EqLookupNodeWithIndexScanFieldOverwrite) {
                                        << "1");
 
     EqLookupNode node(std::move(scanNode),
-                      "col",
+                      NamespaceString("db.col"),
                       "local",
                       "foreign",
                       "b",
@@ -1242,7 +1242,7 @@ TEST(QuerySolutionTest, FieldAvailabilityOutputStreamOperator) {
 TEST(QuerySolutionTest, GetSecondaryNamespaceVectorOverSingleEqLookupNode) {
     auto scanNode = std::make_unique<IndexScanNode>(buildSimpleIndexEntry(BSON("a" << 1)));
     const NamespaceString mainNss("db.main");
-    const auto foreignColl = "db.col";
+    const NamespaceString foreignColl("db.col");
     auto root = std::make_unique<EqLookupNode>(std::move(scanNode),
                                                foreignColl,
                                                "local",
@@ -1257,7 +1257,7 @@ TEST(QuerySolutionTest, GetSecondaryNamespaceVectorOverSingleEqLookupNode) {
     qs.setRoot(std::move(root));
 
     // The output vector should only contain 'foreignColl'.
-    std::vector<NamespaceStringOrUUID> expectedNssVector{NamespaceString(foreignColl)};
+    std::vector<NamespaceStringOrUUID> expectedNssVector{foreignColl};
     assertNamespaceVectorsAreEqual(qs.getAllSecondaryNamespaces(mainNss), expectedNssVector);
 }
 
@@ -1265,7 +1265,7 @@ TEST(QuerySolutionTest, GetSecondaryNamespaceVectorDeduplicatesMainNss) {
     auto scanNode = std::make_unique<IndexScanNode>(buildSimpleIndexEntry(BSON("a" << 1)));
     const NamespaceString mainNss("db.main");
     auto root = std::make_unique<EqLookupNode>(std::move(scanNode),
-                                               mainNss.toString(),
+                                               mainNss,
                                                "local",
                                                "remote",
                                                "b",
@@ -1286,8 +1286,8 @@ TEST(QuerySolutionTest, GetSecondaryNamespaceVectorDeduplicatesMainNss) {
 TEST(QuerySolutionTest, GetSecondaryNamespaceVectorOverNestedEqLookupNodes) {
     auto scanNode = std::make_unique<IndexScanNode>(buildSimpleIndexEntry(BSON("a" << 1)));
     const NamespaceString mainNss("db.main");
-    const auto foreignCollOne = "db.col";
-    const auto foreignCollTwo = "db.foo";
+    const NamespaceString foreignCollOne("db.col");
+    const NamespaceString foreignCollTwo("db.foo");
     auto childEqLookupNode =
         std::make_unique<EqLookupNode>(std::move(scanNode),
                                        foreignCollOne,
@@ -1314,15 +1314,14 @@ TEST(QuerySolutionTest, GetSecondaryNamespaceVectorOverNestedEqLookupNodes) {
     // The foreign collections are unique, so our output vector should contain both of them. Note
     // that because 'getAllSecondaryNamespaces' uses a set internally, these namespaces are
     // expected to be in sorted order in the output vector.
-    std::vector<NamespaceStringOrUUID> expectedNssVector{NamespaceString(foreignCollOne),
-                                                         NamespaceString(foreignCollTwo)};
+    std::vector<NamespaceStringOrUUID> expectedNssVector{foreignCollOne, foreignCollTwo};
     assertNamespaceVectorsAreEqual(qs.getAllSecondaryNamespaces(mainNss), expectedNssVector);
 }
 
 TEST(QuerySolutionTest, GetSecondaryNamespaceVectorDeduplicatesNestedEqLookupNodes) {
     auto scanNode = std::make_unique<IndexScanNode>(buildSimpleIndexEntry(BSON("a" << 1)));
     const NamespaceString mainNss("db.main");
-    const auto foreignColl = "db.col";
+    const NamespaceString foreignColl("db.col");
     auto childEqLookupNode =
         std::make_unique<EqLookupNode>(std::move(scanNode),
                                        foreignColl,
@@ -1348,7 +1347,7 @@ TEST(QuerySolutionTest, GetSecondaryNamespaceVectorDeduplicatesNestedEqLookupNod
 
     // Both nodes reference the same foreign collection. Therefore, our output vector should contain
     // a single copy of that namespace.
-    std::vector<NamespaceStringOrUUID> expectedNssVector{NamespaceString(foreignColl)};
+    std::vector<NamespaceStringOrUUID> expectedNssVector{foreignColl};
     assertNamespaceVectorsAreEqual(qs.getAllSecondaryNamespaces(mainNss), expectedNssVector);
 }
 }  // namespace
diff --git a/src/mongo/db/query/sbe_cached_solution_planner.cpp b/src/mongo/db/query/sbe_cached_solution_planner.cpp
index 416610f401f..72f53591409 100644
--- a/src/mongo/db/query/sbe_cached_solution_planner.cpp
+++ b/src/mongo/db/query/sbe_cached_solution_planner.cpp
@@ -37,6 +37,7 @@
 #include "mongo/db/query/explain.h"
 #include "mongo/db/query/get_executor.h"
 #include "mongo/db/query/plan_cache_key_factory.h"
+#include "mongo/db/query/planner_analysis.h"
 #include "mongo/db/query/query_planner.h"
 #include "mongo/db/query/sbe_multi_planner.h"
 #include "mongo/db/query/stage_builder_util.h"
@@ -50,29 +51,70 @@ namespace mongo::sbe {
 CandidatePlans CachedSolutionPlanner::plan(
     std::vector<std::unique_ptr<QuerySolution>> solutions,
     std::vector<std::pair<std::unique_ptr<PlanStage>, stage_builder::PlanStageData>> roots) {
-
-    // If the cached plan is accepted we'd like to keep the results from the trials even if there
-    // are parts of agg pipelines being lowered into SBE, so we run the trial with the extended
-    // plan. This works because TrialRunTracker, attached to HashAgg stage in $group queries, tracks
-    // as "results" the results of its child stage. For $lookup queries, the TrialRunTracker will
-    // only track the number of reads from the local side. Thus, we can use the number of reads the
-    // plan was cached with during multiplanning even though multiplanning ran trials of
-    // pre-extended plans.
-    //
-    // When "featureFlagSbeFull" is enabled we use the SBE plan cache. The SBE plan cache stores the
-    // entire plan, including the part for any agg pipeline pushed down to SBE. Therefore, this
-    // logic is only necessary when "featureFlagSbeFull" is disabled.
-    if (!_cq.pipeline().empty() && !feature_flags::gFeatureFlagSbeFull.isEnabledAndIgnoreFCV()) {
-        _yieldPolicy->clearRegisteredPlans();
+    if (!_cq.pipeline().empty()) {
+        // When "featureFlagSbeFull" is enabled we use the SBE plan cache. If the plan cache is
+        // enabled we'd like to check if there is any foreign collection in the hash_lookup stage
+        // that is no longer eligible for it. In this case we invalidate the cache and immediately
+        // replan without ever running a trial period.
         auto secondaryCollectionsInfo =
             fillOutSecondaryCollectionsInformation(_opCtx, _collections, &_cq);
-        solutions[0] = QueryPlanner::extendWithAggPipeline(
-            _cq, std::move(solutions[0]), secondaryCollectionsInfo);
-        roots[0] = stage_builder::buildSlotBasedExecutableTree(
-            _opCtx, _collections, _cq, *solutions[0], _yieldPolicy);
+
+        if (feature_flags::gFeatureFlagSbeFull.isEnabledAndIgnoreFCV()) {
+            for (const auto foreignCollection : roots[0].second.foreignHashJoinCollections) {
+                const auto collectionInfo = secondaryCollectionsInfo.find(foreignCollection);
+                tassert(6693500,
+                        "Foreign collection must be present in the collections info",
+                        collectionInfo != secondaryCollectionsInfo.end());
+                tassert(6693501, "Foreign collection must exist", collectionInfo->second.exists);
+
+                if (!QueryPlannerAnalysis::isEligibleForHashJoin(collectionInfo->second)) {
+                    return replan(/* shouldCache */ true,
+                                  str::stream() << "Foreign collection " << foreignCollection
+                                                << " is not eligible for hash join anymore");
+                }
+            }
+        } else {
+            // The SBE plan cache is not enabled. If the cached plan is accepted we'd like to keep
+            // the results from the trials even if there are parts of agg pipelines being lowered
+            // into SBE, so we run the trial with the extended plan. This works because
+            // TrialRunTracker, attached to HashAgg stage in $group queries, tracks as "results" the
+            // results of its child stage. For $lookup queries, the TrialRunTracker will only track
+            // the number of reads from the local side. Thus, we can use the number of reads the
+            // plan was cached with during multiplanning even though multiplanning ran trials of
+            // pre-extended plans.
+            //
+            // The SBE plan cache stores the entire plan, including the part for any agg pipeline
+            // pushed down to SBE. Therefore, this logic is only necessary when "featureFlagSbeFull"
+            // is disabled.
+            _yieldPolicy->clearRegisteredPlans();
+            solutions[0] = QueryPlanner::extendWithAggPipeline(
+                _cq, std::move(solutions[0]), secondaryCollectionsInfo);
+            roots[0] = stage_builder::buildSlotBasedExecutableTree(
+                _opCtx, _collections, _cq, *solutions[0], _yieldPolicy);
+        }
     }
 
-    const size_t maxReadsBeforeReplan = internalQueryCacheEvictionRatio * _decisionReads;
+    // If the '_decisionReads' is not present then we do not run a trial period, keeping the current
+    // plan.
+    if (!_decisionReads) {
+        const auto status = prepareExecutionPlan(
+            roots[0].first.get(), &roots[0].second, true /* preparingFromCache */);
+        uassertStatusOK(status);
+        bool exitedEarly;
+
+        // Discarding SlotAccessor pointers as they will be reacquired later.
+        std::tie(std::ignore, std::ignore, exitedEarly) = status.getValue();
+        tassert(
+            6693502, "TrialRunTracker is not attached therefore can not exit early", !exitedEarly);
+        return {makeVector(plan_ranker::CandidatePlan{std::move(solutions[0]),
+                                                      std::move(roots[0].first),
+                                                      std::move(roots[0].second),
+                                                      false /* exitedEarly*/,
+                                                      Status::OK()}),
+                0};
+    }
+
+    const size_t maxReadsBeforeReplan = internalQueryCacheEvictionRatio * _decisionReads.get();
 
     // In cached solution planning we collect execution stats with an upper bound on reads allowed
     // per trial run computed based on previous decision reads. If the trial run ends before
@@ -122,14 +164,14 @@ CandidatePlans CachedSolutionPlanner::plan(
         "Evicting cache entry for a query and replanning it since the number of required reads "
         "mismatch the number of cached reads",
         "maxReadsBeforeReplan"_attr = maxReadsBeforeReplan,
-        "decisionReads"_attr = _decisionReads,
+        "decisionReads"_attr = *_decisionReads,
         "query"_attr = redact(_cq.toStringShort()),
         "planSummary"_attr = explainer->getPlanSummary());
     return replan(
         true,
         str::stream()
             << "cached plan was less efficient than expected: expected trial execution to take "
-            << _decisionReads << " reads but it took at least " << numReads << " reads");
+            << *_decisionReads << " reads but it took at least " << numReads << " reads");
 }
 
 plan_ranker::CandidatePlan CachedSolutionPlanner::collectExecutionStatsForCachedPlan(
@@ -209,6 +251,13 @@ CandidatePlans CachedSolutionPlanner::replan(bool shouldCache, std::string reaso
     auto solutions = uassertStatusOK(std::move(statusWithMultiPlanSolns));
 
     if (solutions.size() == 1) {
+        if (!_cq.pipeline().empty()) {
+            auto secondaryCollectionsInfo =
+                fillOutSecondaryCollectionsInformation(_opCtx, _collections, &_cq);
+            solutions[0] = QueryPlanner::extendWithAggPipeline(
+                _cq, std::move(solutions[0]), secondaryCollectionsInfo);
+        }
+
         // Only one possible plan. Build the stages from the solution.
         auto [root, data] = buildExecutableTree(*solutions[0]);
         auto status = prepareExecutionPlan(root.get(), &data);
diff --git a/src/mongo/db/query/sbe_cached_solution_planner.h b/src/mongo/db/query/sbe_cached_solution_planner.h
index 0fa3d1cbb14..5070c4f25c8 100644
--- a/src/mongo/db/query/sbe_cached_solution_planner.h
+++ b/src/mongo/db/query/sbe_cached_solution_planner.h
@@ -48,7 +48,7 @@ public:
                           const MultipleCollectionAccessor& collections,
                           const CanonicalQuery& cq,
                           const QueryPlannerParams& queryParams,
-                          size_t decisionReads,
+                          boost::optional<size_t> decisionReads,
                           PlanYieldPolicySBE* yieldPolicy)
         : BaseRuntimePlanner{opCtx, collections, cq, queryParams, yieldPolicy},
           _decisionReads{decisionReads} {}
@@ -96,7 +96,7 @@ private:
     CandidatePlans replan(bool shouldCache, std::string reason) const;
 
     // The number of physical reads taken to decide on a winning plan when the plan was first
-    // cached.
-    const size_t _decisionReads;
+    // cached. boost::none in case planing will not be based on the trial run logic.
+    const boost::optional<size_t> _decisionReads;
 };
 }  // namespace mongo::sbe
diff --git a/src/mongo/db/query/sbe_stage_builder.h b/src/mongo/db/query/sbe_stage_builder.h
index 7abd0e2fa46..ab928f14329 100644
--- a/src/mongo/db/query/sbe_stage_builder.h
+++ b/src/mongo/db/query/sbe_stage_builder.h
@@ -374,6 +374,10 @@ struct PlanStageData {
     // every index used by the plan.
     std::vector<IndexBoundsEvaluationInfo> indexBoundsEvaluationInfos;
 
+    // Stores all namespaces involved in the build side of a hash join plan. Needed to check if the
+    // plan should be evicted as the size of the foreign namespace changes.
+    stdx::unordered_set<NamespaceString> foreignHashJoinCollections;
+
 private:
     // This copy function copies data from 'other' but will not create a copy of its
     // RuntimeEnvironment and CompileCtx.
@@ -397,6 +401,7 @@ private:
         inputParamToSlotMap = other.inputParamToSlotMap;
         variableIdToSlotMap = other.variableIdToSlotMap;
         indexBoundsEvaluationInfos = other.indexBoundsEvaluationInfos;
+        foreignHashJoinCollections = other.foreignHashJoinCollections;
     }
 };
 
diff --git a/src/mongo/db/query/sbe_stage_builder_lookup.cpp b/src/mongo/db/query/sbe_stage_builder_lookup.cpp
index 4525bedd4f7..a83614792e9 100644
--- a/src/mongo/db/query/sbe_stage_builder_lookup.cpp
+++ b/src/mongo/db/query/sbe_stage_builder_lookup.cpp
@@ -1053,6 +1053,9 @@ std::pair<SlotId, std::unique_ptr<sbe::PlanStage>> buildLookupResultObject(
 std::pair<std::unique_ptr<sbe::PlanStage>, PlanStageSlots> SlotBasedStageBuilder::buildLookup(
     const QuerySolutionNode* root, const PlanStageReqs& reqs) {
     const auto eqLookupNode = static_cast<const EqLookupNode*>(root);
+    if (eqLookupNode->lookupStrategy == EqLookupNode::LookupStrategy::kHashJoin) {
+        _state.data->foreignHashJoinCollections.emplace(eqLookupNode->foreignCollection);
+    }
 
     // $lookup creates its own output documents.
     _shouldProduceRecordIdSlot = false;
diff --git a/src/mongo/db/query/sbe_stage_builder_lookup_test.cpp b/src/mongo/db/query/sbe_stage_builder_lookup_test.cpp
index 36e7fee3c09..2a2b8041ff0 100644
--- a/src/mongo/db/query/sbe_stage_builder_lookup_test.cpp
+++ b/src/mongo/db/query/sbe_stage_builder_lookup_test.cpp
@@ -119,9 +119,8 @@ public:
         localScanNode->name = _nss.toString();
 
         // Construct logical query solution.
-        auto foreignCollName = _foreignNss.toString();
         auto lookupNode = std::make_unique<EqLookupNode>(std::move(localScanNode),
-                                                         foreignCollName,
+                                                         _foreignNss,
                                                          localKey,
                                                          foreignKey,
                                                          asKey,