diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 99c5ad9b4a..353dc116f4 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -2291,6 +2291,20 @@ cost_group(Path *path, PlannerInfo *root,
 }
 
 /*
+ * estimate_join_rows
+ *		Set rows of a join path according to its parent relation or according
+ *		to parameters.
+ */
+static void
+estimate_join_rows(PlannerInfo *root, Path *path)
+{
+	if (path->param_info)
+		path->rows = path->param_info->ppi_rows;
+	else
+		path->rows = path->parent->rows;
+}
+
+/*
  * initial_cost_nestloop
  *	  Preliminary estimate of the cost of a nestloop join path.
  *
@@ -2411,10 +2425,7 @@ final_cost_nestloop(PlannerInfo *root, NestPath *path,
 		inner_path_rows = 1;
 
 	/* Mark the path with the correct row estimate */
-	if (path->path.param_info)
-		path->path.rows = path->path.param_info->ppi_rows;
-	else
-		path->path.rows = path->path.parent->rows;
+	estimate_join_rows(root, (Path *) path);
 
 	/* For partial paths, scale row estimate. */
 	if (path->path.parallel_workers > 0)
@@ -2857,10 +2868,7 @@ final_cost_mergejoin(PlannerInfo *root, MergePath *path,
 		inner_path_rows = 1;
 
 	/* Mark the path with the correct row estimate */
-	if (path->jpath.path.param_info)
-		path->jpath.path.rows = path->jpath.path.param_info->ppi_rows;
-	else
-		path->jpath.path.rows = path->jpath.path.parent->rows;
+	estimate_join_rows(root, (Path *) path);
 
 	/* For partial paths, scale row estimate. */
 	if (path->jpath.path.parallel_workers > 0)
@@ -3287,10 +3295,7 @@ final_cost_hashjoin(PlannerInfo *root, HashPath *path,
 	ListCell   *hcl;
 
 	/* Mark the path with the correct row estimate */
-	if (path->jpath.path.param_info)
-		path->jpath.path.rows = path->jpath.path.param_info->ppi_rows;
-	else
-		path->jpath.path.rows = path->jpath.path.parent->rows;
+	estimate_join_rows(root, (Path *) path);
 
 	/* For partial paths, scale row estimate. */
 	if (path->jpath.path.parallel_workers > 0)