diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 7bf67a0..480fd25 100644
*** a/src/backend/optimizer/path/costsize.c
--- b/src/backend/optimizer/path/costsize.c
*************** final_cost_mergejoin(PlannerInfo *root, 
*** 2941,2948 ****
  		if (rescannedtuples < 0)
  			rescannedtuples = 0;
  	}
! 	/* We'll inflate various costs this much to account for rescanning */
! 	rescanratio = 1.0 + (rescannedtuples / inner_path_rows);
  
  	/*
  	 * Decide whether we want to materialize the inner input to shield it from
--- 2941,2953 ----
  		if (rescannedtuples < 0)
  			rescannedtuples = 0;
  	}
! 
! 	/*
! 	 * We'll inflate various costs this much to account for rescanning.  Note
! 	 * that this is to be multiplied by something involving inner_rows, or
! 	 * another number related to the portion of the inner rel we'll scan.
! 	 */
! 	rescanratio = 1.0 + (rescannedtuples / inner_rows);
  
  	/*
  	 * Decide whether we want to materialize the inner input to shield it from
*************** final_cost_mergejoin(PlannerInfo *root, 
*** 2969,2975 ****
  	 * of the generated Material node.
  	 */
  	mat_inner_cost = inner_run_cost +
! 		cpu_operator_cost * inner_path_rows * rescanratio;
  
  	/*
  	 * If we don't need mark/restore at all, we don't need materialization.
--- 2974,2980 ----
  	 * of the generated Material node.
  	 */
  	mat_inner_cost = inner_run_cost +
! 		cpu_operator_cost * inner_rows * rescanratio;
  
  	/*
  	 * If we don't need mark/restore at all, we don't need materialization.