fix_row_est_pa_v1.patch

diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c
index 0e93713..3920f53 100644
--- a/src/backend/executor/nodeAppend.c
+++ b/src/backend/executor/nodeAppend.c
@@ -446,10 +446,9 @@ choose_next_subplan_for_leader(AppendState *node)
  *
  *		We start from the first plan and advance through the list;
  *		when we get back to the end, we loop back to the first
- *		nonpartial plan.  This assigns the non-partial plans first
- *		in order of descending cost and then spreads out the
- *		workers as evenly as possible across the remaining partial
- *		plans.
+ *		partial plan.  This assigns the non-partial plans first in
+ *		order of descending cost and then spreads out the workers
+ *		as evenly as possible across the remaining partial plans.
  * ----------------------------------------------------------------
  */
 static bool
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index c3daacd..2dacdad 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -1870,6 +1870,7 @@ cost_append(AppendPath *apath)
 		foreach(l, apath->subpaths)
 		{
 			Path	   *subpath = (Path *) lfirst(l);
+			double		subpath_parallel_divisor = get_parallel_divisor(subpath);
 
 			/*
 			 * Append will start returning tuples when the child node having
@@ -1883,18 +1884,23 @@ cost_append(AppendPath *apath)
 											   subpath->startup_cost);
 
 			/*
-			 * Apply parallel divisor to non-partial subpaths.  Also add the
-			 * cost of partial paths to the total cost, but ignore non-partial
-			 * paths for now.
+			 * Apply parallel divisor to subpaths.  Scale the value of
+			 * parallel divisor for partial paths as the number of rows
+			 * computed for them might have used a different value for it.
+			 * Also add the cost of partial paths to the total cost, but
+			 * ignore non-partial paths for now.
 			 */
 			if (i < apath->first_partial_path)
 				apath->path.rows += subpath->rows / parallel_divisor;
 			else
 			{
-				apath->path.rows += subpath->rows;
+				apath->path.rows += (subpath->rows * subpath_parallel_divisor /
+					parallel_divisor);
 				apath->path.total_cost += subpath->total_cost;
 			}
 
+			apath->path.rows = clamp_row_est(apath->path.rows);
+
 			i++;
 		}