diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
new file mode 100644
index 0caac75..f98195e
*** a/src/backend/optimizer/path/costsize.c
--- b/src/backend/optimizer/path/costsize.c
*************** final_cost_mergejoin(PlannerInfo *root, 
*** 2242,2247 ****
--- 2242,2250 ----
  	mat_inner_cost = inner_run_cost +
  		cpu_operator_cost * inner_path_rows * rescanratio;
  
+ 	if (!enable_material)
+ 		mat_inner_cost += disable_cost;
+ 
  	/*
  	 * Prefer materializing if it looks cheaper, unless the user has asked to
  	 * suppress materialization.