SERVER-63050 add ability to check if no foreign namespaces are involved in an aggregation

2 files changed, 12 insertions, 0 deletions

diff --git a/src/mongo/db/namespace_string.h b/src/mongo/db/namespace_string.h
index 505eb9d3130..f511a6a3f04 100644
--- a/src/mongo/db/namespace_string.h
+++ b/src/mongo/db/namespace_string.h
@@ -452,6 +452,9 @@ public:
         return coll().startsWith("$cmd."_sd);
     }
 
+    /**
+     * NOTE an aggregate could still refer to another collection using a stage like $out.
+     */
     bool isCollectionlessAggregateNS() const;
     bool isListCollectionsCursorNS() const;
 
diff --git a/src/mongo/db/pipeline/expression_context.h b/src/mongo/db/pipeline/expression_context.h
index 9334cd4ecff..15a0d15ed48 100644
--- a/src/mongo/db/pipeline/expression_context.h
+++ b/src/mongo/db/pipeline/expression_context.h
@@ -290,6 +290,15 @@ public:
     };
 
     /**
+     * Returns true if there are no namespaces in the query other than the namespace the query was
+     * issued against. eg if there is no $out, $lookup ect. If namespaces have not yet been resolved
+     * then it will also return false.
+     */
+    bool noForeignNamespaces() const {
+        return _resolvedNamespaces.empty();
+    }
+
+    /**
      * Convenience call that returns true if the tailableMode indicates a tailable and awaitData
      * query.
      */