[CF 4285] v1 - Revise get_cheapest_parallel_safe_total_inner

This branch was automatically generated by a robot using patches from an
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https://commitfest.postgresql.org/patch/4285

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Patch(es): https://www.postgresql.org/message-id/CAMbWs49xR_2T1BPDw+vO4Bs7pqYiQn4aNaWdmA9BdVEaHhtktg@mail.gmail.com
Author(s): Richard Guo

Author: Commitfest Bot

src/backend/optimizer/path/pathkeys.c

@@ -698,18 +698,25 @@ get_cheapest_fractional_path_for_pathkeys(List *paths,
 Path *
 get_cheapest_parallel_safe_total_inner(List *paths)
 {
+	Path	   *matched_path = NULL;
 	ListCell   *l;
 
 	foreach(l, paths)
 	{
 		Path	   *innerpath = (Path *) lfirst(l);
 
-		if (innerpath->parallel_safe &&
-			bms_is_empty(PATH_REQ_OUTER(innerpath)))
-			return innerpath;
+		if (!innerpath->parallel_safe ||
+			!bms_is_empty(PATH_REQ_OUTER(innerpath)))
+			continue;
+
+		if (matched_path != NULL &&
+			compare_path_costs(matched_path, innerpath, TOTAL_COST) <= 0)
+			continue;
+
+		matched_path = innerpath;
 	}
 
-	return NULL;
+	return matched_path;
 }
 
 /****************************************************************************