diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 8937e71..5f2ddae 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1682,7 +1682,8 @@ grouping_planner(PlannerInfo *root, bool inheritance_update,
 			scanjoin_target = grouping_target;
 
 		/*
-		 * Forcibly apply that target to all the Paths for the scan/join rel.
+		 * Forcibly apply that target to all the Paths and Partial Paths for
+		 * the scan/join rel.
 		 *
 		 * In principle we should re-run set_cheapest() here to identify the
 		 * cheapest path, but it seems unlikely that adding the same tlist
@@ -1710,6 +1711,19 @@ grouping_planner(PlannerInfo *root, bool inheritance_update,
 			}
 		}
 
+		foreach(lc, current_rel->partial_pathlist)
+		{
+			Path	   *subpath = (Path *) lfirst(lc);
+			Path	   *path;
+
+			Assert(subpath->param_info == NULL);
+			path = apply_projection_to_path(root, current_rel,
+											subpath, scanjoin_target);
+			/* If we had to add a Result, path is different from subpath */
+			if (path != subpath)
+				lfirst(lc) = path;
+		}
+
 		/*
 		 * If we have grouping and/or aggregation, consider ways to implement
 		 * that.  We build a new upperrel representing the output of this