diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 7935d6b995..7b234224e1 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.60 1999/02/04 01:46:53 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.61 1999/02/04 03:19:06 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1397,13 +1397,13 @@ _copyHashInfo(HashInfo *from)
 }
 
 /* ----------------
- *		_copyMInfo
+ *		_copyMergeInfo
  * ----------------
  */
-static MInfo *
-_copyMInfo(MInfo *from)
+static MergeInfo *
+_copyMergeInfo(MergeInfo *from)
 {
-	MInfo	   *newnode = makeNode(MInfo);
+	MergeInfo	   *newnode = makeNode(MergeInfo);
 
 	/* ----------------
 	 *	copy remainder of node
@@ -1800,8 +1800,8 @@ copyObject(void *from)
 		case T_HashInfo:
 			retval = _copyHashInfo(from);
 			break;
-		case T_MInfo:
-			retval = _copyMInfo(from);
+		case T_MergeInfo:
+			retval = _copyMergeInfo(from);
 			break;
 		case T_JoinInfo:
 			retval = _copyJoinInfo(from);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index fc7a1b4438..f3ac661b0a 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.47 1999/02/04 01:46:54 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.48 1999/02/04 03:19:06 momjian Exp $
  *
  * NOTES
  *	  Most of the read functions for plan nodes are tested. (In fact, they
@@ -1914,7 +1914,7 @@ _readJoinMethod()
 static HashInfo *
 _readHashInfo()
 {
-	HashInfo	   *local_node;
+	HashInfo	*local_node;
 	char	   *token;
 	int			length;
 
diff --git a/src/backend/optimizer/README b/src/backend/optimizer/README
index bf67e97e38..6d9dae115c 100644
--- a/src/backend/optimizer/README
+++ b/src/backend/optimizer/README
@@ -1,3 +1,6 @@
+Optimizer Functions
+-------------------
+
 These directories take the Query structure returned by the parser, and
 generate a plan used by the executor.  The /plan directory generates the
 plan, the /path generates all possible ways to join the tables, and
@@ -93,9 +96,18 @@ planner()
 
 Optimizer Structures
 --------------------
-RelOptInfo		- info about every relation
-  RestrictInfo	- info about restrictions
-  JoinInfo		- info about join combinations
-  Path			- info about every way to access a relation(sequential, index)
-    PathOrder 	- info about every ordering (sort, merge of relations)
+
+RelOptInfo		- Every relation
+
+ RestrictInfo	- restriction clauses
+ JoinInfo		- join combinations
+
+ Path			- every way to access a relation(sequential, index)
+  IndexPath		- index scans
+
+  JoinPath		- joins
+   MergePath	- merge joins
+   HashPath		- hash joins
+
+ PathOrder		- every ordering type (sort, merge of relations)
 
diff --git a/src/backend/optimizer/path/hashutils.c b/src/backend/optimizer/path/hashutils.c
index 4cdf4752d3..1eebfa9b75 100644
--- a/src/backend/optimizer/path/hashutils.c
+++ b/src/backend/optimizer/path/hashutils.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/hashutils.c,v 1.10 1999/02/04 01:46:57 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/hashutils.c,v 1.11 1999/02/04 03:19:08 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,7 +54,7 @@ group_clauses_by_hashop(List *restrictinfo_list,
 		 */
 		if (hashjoinop)
 		{
-			HashInfo	   *xhashinfo = (HashInfo *) NULL;
+			HashInfo   *xhashinfo = (HashInfo *) NULL;
 			Expr	   *clause = restrictinfo->clause;
 			Var		   *leftop = get_leftop(clause);
 			Var		   *rightop = get_rightop(clause);
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 991290178f..7a5f4889b1 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.13 1999/02/04 01:46:57 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.14 1999/02/04 03:19:08 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -162,7 +162,6 @@ find_all_join_paths(Query *root, List *joinrels)
 		temp_list = innerrel->pathlist;
 		foreach(path, temp_list)
 		{
-
 			/*
 			 * XXX
 			 *
@@ -235,7 +234,7 @@ sort_inner_and_outer(RelOptInfo * joinrel,
 					 List *mergeinfo_list)
 {
 	List	   *ms_list = NIL;
-	MInfo	   *xmergeinfo = (MInfo *) NULL;
+	MergeInfo	   *xmergeinfo = (MergeInfo *) NULL;
 	MergePath  *temp_node = (MergePath *) NULL;
 	List	   *i;
 	List	   *outerkeys = NIL;
@@ -244,7 +243,7 @@ sort_inner_and_outer(RelOptInfo * joinrel,
 
 	foreach(i, mergeinfo_list)
 	{
-		xmergeinfo = (MInfo *) lfirst(i);
+		xmergeinfo = (MergeInfo *) lfirst(i);
 
 		outerkeys = extract_path_keys(xmergeinfo->jmethod.jmkeys,
 							  outerrel->targetlist,
@@ -325,7 +324,7 @@ match_unsorted_outer(RelOptInfo * joinrel,
 		List	   *clauses = NIL;
 		List	   *matchedJoinKeys = NIL;
 		List	   *matchedJoinClauses = NIL;
-		MInfo	   *xmergeinfo = (MInfo *) NULL;
+		MergeInfo	   *xmergeinfo = (MergeInfo *) NULL;
 
 		outerpath = (Path *) lfirst(i);
 
@@ -465,7 +464,7 @@ match_unsorted_inner(RelOptInfo * joinrel,
 
 	foreach(i, innerpath_list)
 	{
-		MInfo	   *xmergeinfo = (MInfo *) NULL;
+		MergeInfo	   *xmergeinfo = (MergeInfo *) NULL;
 		List	   *clauses = NIL;
 		List	   *matchedJoinKeys = NIL;
 		List	   *matchedJoinClauses = NIL;
@@ -579,7 +578,7 @@ hash_inner_and_outer(RelOptInfo * joinrel,
 					 RelOptInfo * innerrel,
 					 List *hashinfo_list)
 {
-	HashInfo	   *xhashinfo = (HashInfo *) NULL;
+	HashInfo   *xhashinfo = (HashInfo *) NULL;
 	List	   *hjoin_list = NIL;
 	HashPath   *temp_node = (HashPath *) NULL;
 	List	   *i = NIL;
diff --git a/src/backend/optimizer/path/mergeutils.c b/src/backend/optimizer/path/mergeutils.c
index 45882728b7..2896c4a6d8 100644
--- a/src/backend/optimizer/path/mergeutils.c
+++ b/src/backend/optimizer/path/mergeutils.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.11 1999/02/03 21:16:27 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.12 1999/02/04 03:19:09 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,7 +53,7 @@ group_clauses_by_order(List *restrictinfo_list,
 			 * if one does not yet exist for this merge ordering.
 			 */
 			PathOrder	p_ordering;
-			MInfo	   *xmergeinfo;
+			MergeInfo	   *xmergeinfo;
 			Expr	   *clause = restrictinfo->clause;
 			Var		   *leftop = get_leftop(clause);
 			Var		   *rightop = get_rightop(clause);
@@ -77,7 +77,7 @@ group_clauses_by_order(List *restrictinfo_list,
 
 			if (xmergeinfo == NULL)
 			{
-				xmergeinfo = makeNode(MInfo);
+				xmergeinfo = makeNode(MergeInfo);
 
 				xmergeinfo->m_ordering = merge_ordering;
 				mergeinfo_list = lcons(xmergeinfo,
@@ -102,7 +102,7 @@ group_clauses_by_order(List *restrictinfo_list,
  * Returns the node if it exists.
  *
  */
-MInfo *
+MergeInfo *
 match_order_mergeinfo(PathOrder *ordering, List *mergeinfo_list)
 {
 	MergeOrder *xmergeorder;
@@ -110,7 +110,7 @@ match_order_mergeinfo(PathOrder *ordering, List *mergeinfo_list)
 
 	foreach(xmergeinfo, mergeinfo_list)
 	{
-		MInfo	   *mergeinfo = (MInfo *) lfirst(xmergeinfo);
+		MergeInfo	   *mergeinfo = (MergeInfo *) lfirst(xmergeinfo);
 
 		xmergeorder = mergeinfo->m_ordering;
 
@@ -123,5 +123,5 @@ match_order_mergeinfo(PathOrder *ordering, List *mergeinfo_list)
 			return mergeinfo;
 		}
 	}
-	return (MInfo *) NIL;
+	return (MergeInfo *) NIL;
 }
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index e0c45ea9e1..d001c33c99 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: nodes.h,v 1.37 1999/02/04 01:47:00 momjian Exp $
+ * $Id: nodes.h,v 1.38 1999/02/04 03:19:10 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -82,7 +82,7 @@ typedef enum NodeTag
 	T_RestrictInfo,
 	T_JoinMethod,
 	T_HashInfo,
-	T_MInfo,
+	T_MergeInfo,
 	T_JoinInfo,
 	T_Iter,
 	T_Stream,
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index b0feae341f..45bb715e67 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: relation.h,v 1.13 1999/02/04 01:47:02 momjian Exp $
+ * $Id: relation.h,v 1.14 1999/02/04 03:19:10 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -47,7 +47,7 @@ typedef List *Relid;
  *						leaves the tuples unordered)
  *		cheapestpath -	least expensive Path (regardless of final order)
  *		pruneable - flag to let the planner know whether it can prune the plan
- *					space of this RelOptInfo or not.  -- JMH, 11/11/92
+ *					space of this RelOptInfo or not.
  *
  *	 * If the relation is a (secondary) index it will have the following
  *		three fields:
@@ -157,8 +157,7 @@ typedef struct IndexPath
 	Path		path;
 	List	   *indexid;
 	List	   *indexqual;
-	int		   *indexkeys;		/* to transform heap attnos into index
-								 * ones */
+	int		   *indexkeys;	/* to transform heap attnos into index ones */
 } IndexPath;
 
 typedef struct JoinPath
@@ -236,11 +235,11 @@ typedef struct HashInfo
 	Oid			hashop;
 } HashInfo;
 
-typedef struct MInfo
+typedef struct MergeInfo
 {
 	JoinMethod	jmethod;
 	MergeOrder *m_ordering;
-} MInfo;
+} MergeInfo;
 
 typedef struct JoinInfo
 {
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 99f2edc488..babcd84eaa 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -7,7 +7,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: paths.h,v 1.11 1999/02/03 20:15:53 momjian Exp $
+ * $Id: paths.h,v 1.12 1999/02/04 03:19:11 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -70,7 +70,7 @@ extern List *new_join_pathkeys(List *outer_pathkeys,
  */
 extern List *group_clauses_by_order(List *restrictinfo_list,
 					   int inner_relid);
-extern MInfo *match_order_mergeinfo(PathOrder *ordering,
+extern MergeInfo *match_order_mergeinfo(PathOrder *ordering,
 					  List *mergeinfo_list);
 
 /*