From ae12e25263d6c1c78fe81bc23828eab0563e9d52 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Thu, 4 Feb 1999 19:20:12 +0000
Subject: [PATCH] Update optimizer comments.

---
 src/backend/optimizer/path/prune.c    | 12 +++++++-----
 src/backend/optimizer/util/pathnode.c | 19 +++++++++++--------
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/src/backend/optimizer/path/prune.c b/src/backend/optimizer/path/prune.c
index e65c4d7d67..f3194605c7 100644
--- a/src/backend/optimizer/path/prune.c
+++ b/src/backend/optimizer/path/prune.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/prune.c,v 1.18 1999/02/04 01:46:58 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/prune.c,v 1.19 1999/02/04 19:20:11 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -64,16 +64,18 @@ prune_joinrel(RelOptInfo *rel, List *other_rels)
 	List	   *i = NIL;
 	List	   *result = NIL;
 
-	foreach(i, other_rels)
+	foreach(r1, other_rels)
 	{
-		RelOptInfo *other_rel = (RelOptInfo *) lfirst(i);
+		RelOptInfo *other_rel = (RelOptInfo *) lfirst(r1);
 
 		if (same(rel->relids, other_rel->relids))
-		{
+			/*
+			 *	This are on the same relations,
+			 *	so get the best of their pathlists.
+			 */
 			rel->pathlist = add_pathlist(rel,
 										 rel->pathlist,
 										 other_rel->pathlist);
-		}
 		else
 			result = nconc(result, lcons(other_rel, NIL));
 	}
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index 7bdec4bb4a..e30421c374 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.17 1999/02/04 01:46:59 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.18 1999/02/04 19:20:12 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -101,21 +101,24 @@ set_cheapest(RelOptInfo *parent_rel, List *pathlist)
 List *
 add_pathlist(RelOptInfo *parent_rel, List *unique_paths, List *new_paths)
 {
-	List	   *x;
-	Path	   *new_path;
-	Path	   *old_path;
-	bool		noOther;
+	List	   *p1;
 
-	foreach(x, new_paths)
+	foreach(p1, new_paths)
 	{
-		new_path = (Path *) lfirst(x);
+		Path	   *new_path = (Path *) lfirst(p1);
+ 		Path	   *old_path;
+		bool		noOther;
+
+		/* Is this new path already in unique_paths? */
 		if (member(new_path, unique_paths))
 			continue;
+
+		/* Find best matching path */
 		old_path = better_path(new_path, unique_paths, &noOther);
 
 		if (noOther)
 		{
-			/* Is a brand new path.  */
+			/* This is a brand new path.  */
 			new_path->parent = parent_rel;
 			unique_paths = lcons(new_path, unique_paths);
 		}