MergeSort was sometimes called mergejoin and was confusing. Now

it is now only mergejoin.

src/backend/optimizer/geqo/geqo_eval.c

@@ -5,7 +5,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: geqo_eval.c,v 1.20 1998/07/18 04:22:27 momjian Exp $
+ * $Id: geqo_eval.c,v 1.21 1998/08/04 16:44:02 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -422,8 +422,8 @@ new_joininfo_list(List *joininfo_list, List *join_relids)
 					joininfo->otherrels;
 				other_joininfo->jinfoclauseinfo =
 					joininfo->jinfoclauseinfo;
-				other_joininfo->mergesortable =
-					joininfo->mergesortable;
+				other_joininfo->mergejoinable =
+					joininfo->mergejoinable;
 				other_joininfo->hashjoinable =
 					joininfo->hashjoinable;
 				other_joininfo->inactive = false;
@@ -509,7 +509,7 @@ geqo_add_new_joininfos(Query *root, List *joinrels, List *outerrels)
 			JInfo	   *joininfo = (JInfo *) lfirst(xjoininfo);
 			List	   *other_rels = joininfo->otherrels;
 			List	   *clause_info = joininfo->jinfoclauseinfo;
-			bool		mergesortable = joininfo->mergesortable;
+			bool		mergejoinable = joininfo->mergejoinable;
 			bool		hashjoinable = joininfo->hashjoinable;
 
 			foreach(xrelid, other_rels)
@@ -541,7 +541,7 @@ geqo_add_new_joininfos(Query *root, List *joinrels, List *outerrels)
 
 				new_joininfo->otherrels = joinrel->relids;
 				new_joininfo->jinfoclauseinfo = clause_info;
-				new_joininfo->mergesortable = mergesortable;
+				new_joininfo->mergejoinable = mergejoinable;
 				new_joininfo->hashjoinable = hashjoinable;
 				new_joininfo->inactive = false;
 				rel->joininfo =
@@ -570,7 +570,7 @@ geqo_add_new_joininfos(Query *root, List *joinrels, List *outerrels)
 
 							new_joininfo->otherrels = new_relids;
 							new_joininfo->jinfoclauseinfo = clause_info;
-							new_joininfo->mergesortable = mergesortable;
+							new_joininfo->mergejoinable = mergejoinable;
 							new_joininfo->hashjoinable = hashjoinable;
 							new_joininfo->inactive = false;
 							joinrel->joininfo =

src/backend/optimizer/path/costsize.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.22 1998/07/18 04:22:31 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.23 1998/08/04 16:44:04 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -47,7 +47,7 @@ bool		_enable_indexscan_ = true;
 bool		_enable_sort_ = true;
 bool		_enable_hash_ = true;
 bool		_enable_nestloop_ = true;
-bool		_enable_mergesort_ = true;
+bool		_enable_mergejoin_ = true;
 bool		_enable_hashjoin_ = true;
 
 Cost		_cpu_page_wight_ = _CPU_PAGE_WEIGHT_;
@@ -259,7 +259,7 @@ cost_nestloop(Cost outercost,
 }
 
 /*
- * cost_mergesort--
+ * cost_mergejoin--
  *	  'outercost' and 'innercost' are the (disk+cpu) costs of scanning the
  *				outer and inner relations
  *	  'outersortkeys' and 'innersortkeys' are lists of the keys to be used
@@ -273,7 +273,7 @@ cost_nestloop(Cost outercost,
  *
  */
 Cost
-cost_mergesort(Cost outercost,
+cost_mergejoin(Cost outercost,
 			   Cost innercost,
 			   List *outersortkeys,
 			   List *innersortkeys,
@@ -284,7 +284,7 @@ cost_mergesort(Cost outercost,
 {
 	Cost		temp = 0;
 
-	if (!_enable_mergesort_)
+	if (!_enable_mergejoin_)
 		temp += _disable_cost_;
 
 	temp += outercost;

src/backend/optimizer/path/indxpath.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.24 1998/08/04 00:42:08 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.25 1998/08/04 16:44:06 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1251,7 +1251,7 @@ index_innerjoin(Query *root, RelOptInfo *rel, List *clausegroup_list,
  *
  * 'rel' is the relation for which 'index' is defined
  * 'clausegroup-list' is the list of clause groups (lists of clauseinfo
- *				nodes) grouped by mergesortorder
+ *				nodes) grouped by mergejoinorder
  * 'join' is a flag indicating whether or not the clauses are join
  *				clauses
  *
@@ -1284,7 +1284,7 @@ create_index_paths(Query *root,
 			clauseinfo = (CInfo *) lfirst(j);
 			if (!(join_clause_p((Node *) clauseinfo->clause) &&
 				  equal_path_merge_ordering(index->ordering,
-											clauseinfo->mergesortorder)))
+											clauseinfo->mergejoinorder)))
 				temp = false;
 		}
 

src/backend/optimizer/path/joinpath.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.7 1998/07/18 04:22:32 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.8 1998/08/04 16:44:07 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -27,7 +27,7 @@
 #include "optimizer/pathnode.h"
 #include "optimizer/keys.h"
 #include "optimizer/cost.h"		/* for _enable_{hashjoin,
-								 * _enable_mergesort} */
+								 * _enable_mergejoin} */
 
 static Path *best_innerjoin(List *join_paths, List *outer_relid);
 static List *
@@ -98,7 +98,7 @@ find_all_join_paths(Query *root, List *joinrels)
 
 		bestinnerjoin = best_innerjoin(innerrel->innerjoin,
 									   outerrel->relids);
-		if (_enable_mergesort_)
+		if (_enable_mergejoin_)
 		{
 			mergeinfo_list =
 				group_clauses_by_order(joinrel->clauseinfo,
@@ -116,7 +116,7 @@ find_all_join_paths(Query *root, List *joinrels)
 		joinrel->relids = intAppend(outerrelids, innerrelids);
 
 		/*
-		 * 1. Consider mergesort paths where both relations must be
+		 * 1. Consider mergejoin paths where both relations must be
 		 * explicitly sorted.
 		 */
 		pathlist = sort_inner_and_outer(joinrel, outerrel,
@@ -125,7 +125,7 @@ find_all_join_paths(Query *root, List *joinrels)
 		/*
 		 * 2. Consider paths where the outer relation need not be
 		 * explicitly sorted. This may include either nestloops and
-		 * mergesorts where the outer path is already ordered.
+		 * mergejoins where the outer path is already ordered.
 		 */
 		pathlist =
 			add_pathlist(joinrel, pathlist,
@@ -139,7 +139,7 @@ find_all_join_paths(Query *root, List *joinrels)
 
 		/*
 		 * 3. Consider paths where the inner relation need not be
-		 * explicitly sorted.  This may include nestloops and mergesorts
+		 * explicitly sorted.  This may include nestloops and mergejoins
 		 * the actual nestloop nodes were constructed in
 		 * (match-unsorted-outer).
 		 */
@@ -226,16 +226,16 @@ best_innerjoin(List *join_paths, List *outer_relids)
 
 /*
  * sort-inner-and-outer--
- *	  Create mergesort join paths by explicitly sorting both the outer and
+ *	  Create mergejoin join paths by explicitly sorting both the outer and
  *	  inner join relations on each available merge ordering.
  *
  * 'joinrel' is the join relation
  * 'outerrel' is the outer join relation
  * 'innerrel' is the inner join relation
- * 'mergeinfo-list' is a list of nodes containing info on(mergesortable)
+ * 'mergeinfo-list' is a list of nodes containing info on(mergejoinable)
  *				clauses for joining the relations
  *
- * Returns a list of mergesort paths.
+ * Returns a list of mergejoin paths.
  */
 static List *
 sort_inner_and_outer(RelOptInfo *joinrel,
@@ -270,7 +270,7 @@ sort_inner_and_outer(RelOptInfo *joinrel,
 							  xmergeinfo->jmethod.clauses);
 
 		temp_node =
-			create_mergesort_path(joinrel,
+			create_mergejoin_path(joinrel,
 								  outerrel->size,
 								  innerrel->size,
 								  outerrel->width,
@@ -292,12 +292,12 @@ sort_inner_and_outer(RelOptInfo *joinrel,
  * match-unsorted-outer--
  *	  Creates possible join paths for processing a single join relation
  *	  'joinrel' by employing either iterative substitution or
- *	  mergesorting on each of its possible outer paths(assuming that the
+ *	  mergejoining on each of its possible outer paths(assuming that the
  *	  outer relation need not be explicitly sorted).
  *
  *	  1. The inner path is the cheapest available inner path.
- *	  2. Mergesort wherever possible.  Mergesorts are considered if there
- *		 are mergesortable join clauses between the outer and inner join
+ *	  2. Mergejoin wherever possible.  Mergejoin are considered if there
+ *		 are mergejoinable join clauses between the outer and inner join
  *		 relations such that the outer path is keyed on the variables
  *		 appearing in the clauses.	The corresponding inner merge path is
  *		 either a path whose keys match those of the outer path(if such a
@@ -310,7 +310,7 @@ sort_inner_and_outer(RelOptInfo *joinrel,
  * 'outerpath-list' is the list of possible outer paths
  * 'cheapest-inner' is the cheapest inner path
  * 'best-innerjoin' is the best inner index path(if any)
- * 'mergeinfo-list' is a list of nodes containing info on mergesortable
+ * 'mergeinfo-list' is a list of nodes containing info on mergejoinable
  *		clauses
  *
  * Returns a list of possible join path nodes.
@@ -424,7 +424,7 @@ match_unsorted_outer(RelOptInfo *joinrel,
 				mergeinnerpath = cheapest_inner;
 
 			temp_node =
-				lcons(create_mergesort_path(joinrel,
+				lcons(create_mergejoin_path(joinrel,
 											outerrel->size,
 											innerrel->size,
 											outerrel->width,
@@ -463,7 +463,7 @@ match_unsorted_outer(RelOptInfo *joinrel,
  * 'outerrel' is the outer join relation
  * 'innerrel' is the inner join relation
  * 'innerpath-list' is the list of possible inner join paths
- * 'mergeinfo-list' is a list of nodes containing info on mergesortable
+ * 'mergeinfo-list' is a list of nodes containing info on mergejoinable
  *				clauses
  *
  * Returns a list of possible merge paths.
@@ -542,7 +542,7 @@ match_unsorted_inner(RelOptInfo *joinrel,
 								  clauses);
 
 				temp_node =
-					lcons(create_mergesort_path(joinrel,
+					lcons(create_mergejoin_path(joinrel,
 												outerrel->size,
 												innerrel->size,
 												outerrel->width,

src/backend/optimizer/path/joinrels.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.11 1998/07/18 04:22:33 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.12 1998/08/04 16:44:08 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -360,8 +360,8 @@ new_joininfo_list(List *joininfo_list, List *join_relids)
 					joininfo->otherrels;
 				other_joininfo->jinfoclauseinfo =
 					joininfo->jinfoclauseinfo;
-				other_joininfo->mergesortable =
-					joininfo->mergesortable;
+				other_joininfo->mergejoinable =
+					joininfo->mergejoinable;
 				other_joininfo->hashjoinable =
 					joininfo->hashjoinable;
 				other_joininfo->inactive = false;
@@ -415,7 +415,7 @@ add_new_joininfos(Query *root, List *joinrels, List *outerrels)
 			JInfo	   *joininfo = (JInfo *) lfirst(xjoininfo);
 			List	   *other_rels = joininfo->otherrels;
 			List	   *clause_info = joininfo->jinfoclauseinfo;
-			bool		mergesortable = joininfo->mergesortable;
+			bool		mergejoinable = joininfo->mergejoinable;
 			bool		hashjoinable = joininfo->hashjoinable;
 
 			foreach(xrelid, other_rels)
@@ -428,7 +428,7 @@ add_new_joininfos(Query *root, List *joinrels, List *outerrels)
 
 				new_joininfo->otherrels = joinrel->relids;
 				new_joininfo->jinfoclauseinfo = clause_info;
-				new_joininfo->mergesortable = mergesortable;
+				new_joininfo->mergejoinable = mergejoinable;
 				new_joininfo->hashjoinable = hashjoinable;
 				new_joininfo->inactive = false;
 				rel->joininfo =
@@ -457,7 +457,7 @@ add_new_joininfos(Query *root, List *joinrels, List *outerrels)
 
 							new_joininfo->otherrels = new_relids;
 							new_joininfo->jinfoclauseinfo = clause_info;
-							new_joininfo->mergesortable = mergesortable;
+							new_joininfo->mergejoinable = mergejoinable;
 							new_joininfo->hashjoinable = hashjoinable;
 							new_joininfo->inactive = false;
 							joinrel->joininfo =

src/backend/optimizer/path/mergeutils.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.6 1998/08/04 00:42:09 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.7 1998/08/04 16:44:10 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -23,9 +23,9 @@
 
 /*
  * group-clauses-by-order--
- *	  If a join clause node in 'clauseinfo-list' is mergesortable, store
+ *	  If a join clause node in 'clauseinfo-list' is mergejoinable, store
  *	  it within a mergeinfo node containing other clause nodes with the same
- *	  mergesort ordering.
+ *	  mergejoin ordering.
  *
  * 'clauseinfo-list' is the list of clauseinfo nodes
  * 'inner-relid' is the relid of the inner join relation
@@ -43,7 +43,7 @@ group_clauses_by_order(List *clauseinfo_list,
 	foreach(xclauseinfo, clauseinfo_list)
 	{
 		CInfo	   *clauseinfo = (CInfo *) lfirst(xclauseinfo);
-		MergeOrder *merge_ordering = clauseinfo->mergesortorder;
+		MergeOrder *merge_ordering = clauseinfo->mergejoinorder;
 
 		if (merge_ordering)
 		{

src/backend/optimizer/path/xfunc.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/xfunc.c,v 1.16 1998/07/18 04:22:34 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/xfunc.c,v 1.17 1998/08/04 16:44:11 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1022,7 +1022,7 @@ xfunc_total_path_cost(JoinPath pathnode)
 	{
 		MergePath	mrgnode = (MergePath) pathnode;
 
-		cost += cost_mergesort(get_path_cost((Path) get_outerjoinpath(mrgnode)),
+		cost += cost_mergejoin(get_path_cost((Path) get_outerjoinpath(mrgnode)),
 						get_path_cost((Path) get_innerjoinpath(mrgnode)),
 							   get_outersortkeys(mrgnode),
 							   get_innersortkeys(mrgnode),

src/backend/optimizer/plan/createplan.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.29 1998/07/18 04:22:36 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.30 1998/08/04 16:44:12 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -79,7 +79,7 @@ make_hashjoin(List *tlist, List *qpqual,
 			  List *hashclauses, Plan *lefttree, Plan *righttree);
 static Hash *make_hash(List *tlist, Var *hashkey, Plan *lefttree);
 static MergeJoin *
-make_mergesort(List *tlist, List *qpqual,
+make_mergejoin(List *tlist, List *qpqual,
 			   List *mergeclauses, Oid opcode, Oid *rightorder,
 			   Oid *leftorder, Plan *righttree, Plan *lefttree);
 static Material *
@@ -584,7 +584,7 @@ create_mergejoin_node(MergePath *best_path,
 		inner_node = (Plan *) sorted_inner_node;
 	}
 
-	join_node = make_mergesort(tlist,
+	join_node = make_mergejoin(tlist,
 							   qpqual,
 							   mergeclauses,
 							   opcode,
@@ -1038,7 +1038,7 @@ make_hash(List *tlist, Var *hashkey, Plan *lefttree)
 }
 
 static MergeJoin *
-make_mergesort(List *tlist,
+make_mergejoin(List *tlist,
 			   List *qpqual,
 			   List *mergeclauses,
 			   Oid opcode,
@@ -1058,7 +1058,7 @@ make_mergesort(List *tlist,
 	plan->lefttree = lefttree;
 	plan->righttree = righttree;
 	node->mergeclauses = mergeclauses;
-	node->mergesortop = opcode;
+	node->mergejoinop = opcode;
 	node->mergerightorder = rightorder;
 	node->mergeleftorder = leftorder;
 

src/backend/optimizer/plan/initsplan.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.13 1998/07/18 04:22:37 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.14 1998/08/04 16:44:14 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -41,7 +41,7 @@ add_join_clause_info_to_rels(Query *root, CInfo *clauseinfo,
 							 List *join_relids);
 static void add_vars_to_rels(Query *root, List *vars, List *join_relids);
 
-static MergeOrder *mergesortop(Expr *clause);
+static MergeOrder *mergejoinop(Expr *clause);
 static Oid	hashjoinop(Expr *clause);
 
 
@@ -180,7 +180,7 @@ add_clause_to_rels(Query *root, List *clause)
 	clauseinfo->notclause = contains_not((Node *) clause);
 	clauseinfo->selectivity = 0;
 	clauseinfo->indexids = NIL;
-	clauseinfo->mergesortorder = (MergeOrder *) NULL;
+	clauseinfo->mergejoinorder = (MergeOrder *) NULL;
 	clauseinfo->hashjoinoperator = (Oid) 0;
 
 
@@ -324,8 +324,8 @@ add_vars_to_rels(Query *root, List *vars, List *join_relids)
 
 /*
  * initialize-join-clause-info--
- *	  Set the MergeSortable or HashJoinable field for every joininfo node
- *	  (within a rel node) and the MergeSortOrder or HashJoinOp field for
+ *	  Set the MergeJoinable or HashJoinable field for every joininfo node
+ *	  (within a rel node) and the MergeJoinOrder or HashJoinOp field for
  *	  each clauseinfo node(within a joininfo node) for all relations in a
  *	  query.
  *
@@ -357,15 +357,15 @@ initialize_join_clause_info(List *rel_list)
 					MergeOrder *sortop = (MergeOrder *) NULL;
 					Oid			hashop = (Oid) NULL;
 
-					if (_enable_mergesort_)
-						sortop = mergesortop(clause);
+					if (_enable_mergejoin_)
+						sortop = mergejoinop(clause);
 					if (_enable_hashjoin_)
 						hashop = hashjoinop(clause);
 
 					if (sortop)
 					{
-						clauseinfo->mergesortorder = sortop;
-						joininfo->mergesortable = true;
+						clauseinfo->mergejoinorder = sortop;
+						joininfo->mergejoinable = true;
 					}
 					if (hashop)
 					{
@@ -379,19 +379,19 @@ initialize_join_clause_info(List *rel_list)
 }
 
 /*
- * mergesortop--
- *	  Returns the mergesort operator of an operator iff 'clause' is
- *	  mergesortable, i.e., both operands are single vars and the operator is
- *	  a mergesortable operator.
+ * mergejoinop--
+ *	  Returns the mergejoin operator of an operator iff 'clause' is
+ *	  mergejoinable, i.e., both operands are single vars and the operator is
+ *	  a mergejoinable operator.
  */
 static MergeOrder *
-mergesortop(Expr *clause)
+mergejoinop(Expr *clause)
 {
 	Oid			leftOp,
 				rightOp;
 	bool		sortable;
 
-	sortable = op_mergesortable(((Oper *) clause->oper)->opno,
+	sortable = op_mergejoinable(((Oper *) clause->oper)->opno,
 								(get_leftop(clause))->vartype,
 								(get_rightop(clause))->vartype,
 								&leftOp,

src/backend/optimizer/util/joininfo.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/joininfo.c,v 1.8 1998/07/18 04:22:40 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/joininfo.c,v 1.9 1998/08/04 16:44:17 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -72,7 +72,7 @@ find_joininfo_node(RelOptInfo *this_rel, List *join_relids)
 		joininfo = makeNode(JInfo);
 		joininfo->otherrels = join_relids;
 		joininfo->jinfoclauseinfo = NIL;
-		joininfo->mergesortable = false;
+		joininfo->mergejoinable = false;
 		joininfo->hashjoinable = false;
 		joininfo->inactive = false;
 		this_rel->joininfo = lcons(joininfo, this_rel->joininfo);

src/backend/optimizer/util/pathnode.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.9 1998/07/18 04:22:41 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.10 1998/08/04 16:44:18 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -462,8 +462,8 @@ create_nestloop_path(RelOptInfo *joinrel,
 }
 
 /*
- * create_mergesort_path--
- *	  Creates a pathnode corresponding to a mergesort join between
+ * create_mergejoin_path--
+ *	  Creates a pathnode corresponding to a mergejoin join between
  *	  two relations
  *
  * 'joinrel' is the join relation
@@ -481,7 +481,7 @@ create_nestloop_path(RelOptInfo *joinrel,
  *
  */
 MergePath  *
-create_mergesort_path(RelOptInfo *joinrel,
+create_mergejoin_path(RelOptInfo *joinrel,
 					  int outersize,
 					  int innersize,
 					  int outerwidth,
@@ -509,7 +509,7 @@ create_mergesort_path(RelOptInfo *joinrel,
 	pathnode->outersortkeys = outersortkeys;
 	pathnode->innersortkeys = innersortkeys;
 	pathnode->jpath.path.path_cost =
-		cost_mergesort(outer_path->path_cost,
+		cost_mergejoin(outer_path->path_cost,
 					   inner_path->path_cost,
 					   outersortkeys,
 					   innersortkeys,