1 files changed, 8 insertions, 17 deletions

diff --git a/src/mongo/db/pipeline/document_source_out.h b/src/mongo/db/pipeline/document_source_out.h
index cfd9249146b..906a30f10ee 100644
--- a/src/mongo/db/pipeline/document_source_out.h
+++ b/src/mongo/db/pipeline/document_source_out.h
@@ -65,7 +65,7 @@ public:
 /**
  * Abstract class for the $out aggregation stage.
  */
-class DocumentSourceOut : public DocumentSource {
+class DocumentSourceOut : public DocumentSource, public NeedsMergerDocumentSource {
 public:
     /**
      * A "lite parsed" $out stage is similar to other stages involving foreign collections except in
@@ -125,12 +125,8 @@ public:
                 PositionRequirement::kLast,
                 // A $out to an unsharded collection should merge on the primary shard to perform
                 // local writes. A $out to a sharded collection has no requirement, since each shard
-                // can perform its own portion of the write. We use 'kAnyShard' to direct it to
-                // execute on one of the shards in case some of the writes happen to end up being
-                // local.
-                pExpCtx->mongoProcessInterface->isSharded(pExpCtx->opCtx, _outputNs)
-                    ? HostTypeRequirement::kAnyShard
-                    : HostTypeRequirement::kPrimaryShard,
+                // can perform its own portion of the write.
+                HostTypeRequirement::kPrimaryShard,
                 DiskUseRequirement::kWritesPersistentData,
                 FacetRequirement::kNotAllowed,
                 TransactionRequirement::kNotAllowed};
@@ -144,17 +140,12 @@ public:
         return _mode;
     }
 
-    boost::optional<MergingLogic> mergingLogic() final {
-        // It should always be faster to avoid splitting the pipeline if the output collection is
-        // sharded. If we avoid splitting the pipeline then each shard can perform the writes to the
-        // target collection in parallel.
-        if (pExpCtx->mongoProcessInterface->isSharded(pExpCtx->opCtx, _outputNs)) {
-            return boost::none;
-        }
-        // {shardsStage, mergingStage, sortPattern}
-        return MergingLogic{nullptr, this, boost::none};
+    boost::intrusive_ptr<DocumentSource> getShardSource() final {
+        return nullptr;
+    }
+    MergingLogic mergingLogic() final {
+        return {this};
     }
-
     virtual bool canRunInParallelBeforeOut(
         const std::set<std::string>& nameOfShardKeyFieldsUponEntryToStage) const final {
         // If someone is asking the question, this must be the $out stage in question, so yes!