SERVER-66989 Make HashAgg record store key owned

(cherry picked from commit e399422548621ca737903284e8b435c804bb8254)

3 files changed, 8 insertions, 4 deletions

diff --git a/src/mongo/db/exec/sbe/stages/hash_agg.cpp b/src/mongo/db/exec/sbe/stages/hash_agg.cpp
index 73a2375d417..bdb1f7388a6 100644
--- a/src/mongo/db/exec/sbe/stages/hash_agg.cpp
+++ b/src/mongo/db/exec/sbe/stages/hash_agg.cpp
@@ -501,9 +501,9 @@ PlanState HashAggStage::getNext() {
                 KeyString::TypeBits::fromBuffer(KeyString::Version::kLatestVersion, &valReader);
             _aggValueRecordStore = val;
 
-            BufBuilder buf;
+            _aggKeyRSBuffer.reset();
             _aggKeyRecordStore = value::MaterializedRow::deserializeFromKeyString(
-                decodeKeyString(nextRecord->id, typeBits), &buf);
+                decodeKeyString(nextRecord->id, typeBits), &_aggKeyRSBuffer);
             return trackPlanState(PlanState::ADVANCED);
         } else {
             _rsCursor.reset();
diff --git a/src/mongo/db/exec/sbe/stages/hash_agg.h b/src/mongo/db/exec/sbe/stages/hash_agg.h
index 8c117e8717d..19fbca9d1c7 100644
--- a/src/mongo/db/exec/sbe/stages/hash_agg.h
+++ b/src/mongo/db/exec/sbe/stages/hash_agg.h
@@ -184,6 +184,11 @@ private:
     std::vector<std::unique_ptr<value::MaterializedSingleRowAccessor>> _outRecordStoreKeyAccessors;
     std::vector<std::unique_ptr<value::MaterializedSingleRowAccessor>> _outRecordStoreAggAccessors;
 
+    // This buffer stores values for the spilled '_aggKeyRecordStore' that's loaded into memory from
+    // the '_recordStore'. Values in the '_aggKeyRecordStore' row are pointers that point to data in
+    // this buffer.
+    BufBuilder _aggKeyRSBuffer;
+
     std::vector<value::SlotAccessor*> _seekKeysAccessors;
     value::MaterializedRow _seekKeys;
 
diff --git a/src/mongo/db/exec/sbe/util/spilling.cpp b/src/mongo/db/exec/sbe/util/spilling.cpp
index 45931efec8b..c54f3bfe956 100644
--- a/src/mongo/db/exec/sbe/util/spilling.cpp
+++ b/src/mongo/db/exec/sbe/util/spilling.cpp
@@ -63,8 +63,7 @@ boost::optional<value::MaterializedRow> readFromRecordStore(OperationContext* op
     RecordData record;
     if (rs->findRecord(opCtx, rid, &record)) {
         auto valueReader = BufReader(record.data(), record.size());
-        auto val = value::MaterializedRow::deserializeForSorter(valueReader, {});
-        return val;
+        return value::MaterializedRow::deserializeForSorter(valueReader, {});
     }
     return boost::none;
 }