SERVER-32666 Allow $graphLookup against a sharded collection to execute on mongos

2 files changed, 8 insertions, 9 deletions

diff --git a/src/mongo/db/pipeline/document_source_graph_lookup.h b/src/mongo/db/pipeline/document_source_graph_lookup.h
index 5f1af60d2ce..1c7cdd55924 100644
--- a/src/mongo/db/pipeline/document_source_graph_lookup.h
+++ b/src/mongo/db/pipeline/document_source_graph_lookup.h
@@ -56,9 +56,16 @@ public:
     GetModPathsReturn getModifiedPaths() const final;
 
     StageConstraints constraints(Pipeline::SplitState pipeState) const final {
+        // TODO SERVER-27533 Until we remove the restriction of only performing lookups from mongos,
+        // this stage must run on mongos if the output collection is sharded.
+        HostTypeRequirement hostRequirement =
+            (pExpCtx->inMongos && pExpCtx->mongoProcessInterface->isSharded(pExpCtx->opCtx, _from))
+            ? HostTypeRequirement::kMongoS
+            : HostTypeRequirement::kPrimaryShard;
+
         StageConstraints constraints(StreamType::kStreaming,
                                      PositionRequirement::kNone,
-                                     HostTypeRequirement::kPrimaryShard,
+                                     hostRequirement,
                                      DiskUseRequirement::kNoDiskUse,
                                      FacetRequirement::kAllowed,
                                      TransactionRequirement::kAllowed);
diff --git a/src/mongo/db/pipeline/lite_parsed_document_source.h b/src/mongo/db/pipeline/lite_parsed_document_source.h
index 8f4b85168cc..fc3b88163f3 100644
--- a/src/mongo/db/pipeline/lite_parsed_document_source.h
+++ b/src/mongo/db/pipeline/lite_parsed_document_source.h
@@ -189,14 +189,6 @@ public:
         return _requiredPrivileges;
     }
 
-    /**
-     * Returns true if 'nss' is in the list of foreign namespaces for this DocumentSource. By
-     * default, no involved namespace is allowed to be sharded.
-     */
-    bool allowShardedForeignCollection(NamespaceString nss) const {
-        return (_foreignNssSet.find(nss) == _foreignNssSet.end());
-    }
-
 protected:
     stdx::unordered_set<NamespaceString> _foreignNssSet;