Fix nasty bug in optimization of multiway joins: optimizer

would sometimes generate a plan that omitted a sort step before merge.

src/backend/optimizer/path/hashutils.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/hashutils.c,v 1.14 1999/02/22 05:26:18 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/hashutils.c,v 1.15 1999/04/03 00:18:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,19 +29,20 @@ static HashInfo *match_hashop_hashinfo(Oid hashop, List *hashinfo_list);
  *	  hash operator.
  *
  * 'restrictinfo_list' is the list of restrictinfo nodes
- * 'inner_relid' is the relid of the inner join relation
+ * 'inner_relids' is the list of relids in the inner join relation
+ *   (used to determine whether a join var is inner or outer)
  *
  * Returns the new list of hashinfo nodes.
  *
  */
 List *
 group_clauses_by_hashop(List *restrictinfo_list,
-						int inner_relid)
+						Relids inner_relids)
 {
 	List	   *hashinfo_list = NIL;
-	RestrictInfo *restrictinfo = (RestrictInfo *) NULL;
-	List	   *i = NIL;
-	Oid			hashjoinop = 0;
+	RestrictInfo *restrictinfo;
+	List	   *i;
+	Oid			hashjoinop;
 
 	foreach(i, restrictinfo_list)
 	{
@@ -54,23 +55,21 @@ group_clauses_by_hashop(List *restrictinfo_list,
 		 */
 		if (hashjoinop)
 		{
-			HashInfo   *xhashinfo = (HashInfo *) NULL;
 			Expr	   *clause = restrictinfo->clause;
 			Var		   *leftop = get_leftop(clause);
 			Var		   *rightop = get_rightop(clause);
-			JoinKey    *joinkey = (JoinKey *) NULL;
+			HashInfo   *xhashinfo;
+			JoinKey    *joinkey;
 
 			xhashinfo = match_hashop_hashinfo(hashjoinop, hashinfo_list);
-
-			if (inner_relid == leftop->varno)
+			joinkey = makeNode(JoinKey);
+			if (intMember(leftop->varno, inner_relids))
 			{
-				joinkey = makeNode(JoinKey);
 				joinkey->outer = rightop;
 				joinkey->inner = leftop;
 			}
 			else
 			{
-				joinkey = makeNode(JoinKey);
 				joinkey->outer = leftop;
 				joinkey->inner = rightop;
 			}
@@ -79,16 +78,15 @@ group_clauses_by_hashop(List *restrictinfo_list,
 			{
 				xhashinfo = makeNode(HashInfo);
 				xhashinfo->hashop = hashjoinop;
-
 				xhashinfo->jmethod.jmkeys = NIL;
 				xhashinfo->jmethod.clauses = NIL;
-
 				hashinfo_list = lcons(xhashinfo, hashinfo_list);
 			}
 
-			xhashinfo->jmethod.clauses = lcons(clause, xhashinfo->jmethod.clauses);
-
-			xhashinfo->jmethod.jmkeys = lcons(joinkey, xhashinfo->jmethod.jmkeys);
+			xhashinfo->jmethod.clauses = lcons(clause,
+											   xhashinfo->jmethod.clauses);
+			xhashinfo->jmethod.jmkeys = lcons(joinkey,
+											  xhashinfo->jmethod.jmkeys);
 		}
 	}
 	return hashinfo_list;

src/backend/optimizer/path/joinpath.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.32 1999/02/22 05:26:20 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.33 1999/04/03 00:18:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -97,11 +97,11 @@ update_rels_pathlist_for_joins(Query *root, List *joinrels)
 
 		if (_enable_mergejoin_)
 			mergeinfo_list = group_clauses_by_order(joinrel->restrictinfo,
-									   lfirsti(innerrel->relids));
+													innerrel->relids);
 
 		if (_enable_hashjoin_)
 			hashinfo_list = group_clauses_by_hashop(joinrel->restrictinfo,
-										lfirsti(innerrel->relids));
+													innerrel->relids);
 
 		/* need to flatten the relids list */
 		joinrel->relids = nconc(listCopy(outerrelids),
@@ -173,12 +173,10 @@ best_innerjoin(List *join_paths, Relids outer_relids)
 	{
 		Path	   *path = (Path *) lfirst(join_path);
 
-		if (intMember(lfirsti(path->joinid), outer_relids)
-			&& ((cheapest == NULL ||
-				 path_is_cheaper((Path *) lfirst(join_path), cheapest))))
-		{
-			cheapest = (Path *) lfirst(join_path);
-		}
+		if (intMember(lfirsti(path->joinid), outer_relids) &&
+			(cheapest == NULL ||
+			 path_is_cheaper(path, cheapest)))
+			cheapest = path;
 	}
 	return cheapest;
 }

src/backend/optimizer/path/mergeutils.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.20 1999/03/01 00:10:32 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.21 1999/04/03 00:18:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -36,14 +36,15 @@
  * Something to fix next time...
  *
  * 'restrictinfo_list' is the list of restrictinfo nodes
- * 'inner_relid' is the relid of the inner join relation
+ * 'inner_relids' is the list of relids in the inner join relation
+ *   (used to determine whether a join var is inner or outer)
  *
  * Returns the new list of mergeinfo nodes.
  *
  */
 List *
 group_clauses_by_order(List *restrictinfo_list,
-					   int inner_relid)
+					   Relids inner_relids)
 {
 	List	   *mergeinfo_list = NIL;
 	List	   *xrestrictinfo;
@@ -59,26 +60,25 @@ group_clauses_by_order(List *restrictinfo_list,
 			 * Create a new mergeinfo node and add it to 'mergeinfo_list'
 			 * if one does not yet exist for this merge ordering.
 			 */
-			PathOrder	*pathorder;
-			MergeInfo	*xmergeinfo;
 			Expr	   *clause = restrictinfo->clause;
 			Var		   *leftop = get_leftop(clause);
 			Var		   *rightop = get_rightop(clause);
+			PathOrder	*pathorder;
+			MergeInfo	*xmergeinfo;
 			JoinKey    *jmkeys;
 
 			pathorder = makeNode(PathOrder);
 			pathorder->ordtype = MERGE_ORDER;
 			pathorder->ord.merge = merge_ordering;
 			xmergeinfo = match_order_mergeinfo(pathorder, mergeinfo_list);
-			if (inner_relid == leftop->varno)
+			jmkeys = makeNode(JoinKey);
+			if (intMember(leftop->varno, inner_relids))
 			{
-				jmkeys = makeNode(JoinKey);
 				jmkeys->outer = rightop;
 				jmkeys->inner = leftop;
 			}
 			else
 			{
-				jmkeys = makeNode(JoinKey);
 				jmkeys->outer = leftop;
 				jmkeys->inner = rightop;
 			}
@@ -86,10 +86,8 @@ group_clauses_by_order(List *restrictinfo_list,
 			if (xmergeinfo == NULL)
 			{
 				xmergeinfo = makeNode(MergeInfo);
-
 				xmergeinfo->m_ordering = merge_ordering;
-				mergeinfo_list = lcons(xmergeinfo,
-									   mergeinfo_list);
+				mergeinfo_list = lcons(xmergeinfo, mergeinfo_list);
 			}
 
 			xmergeinfo->jmethod.clauses = lcons(clause,

src/include/optimizer/paths.h

@@ -7,7 +7,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: paths.h,v 1.26 1999/02/22 05:26:52 momjian Exp $
+ * $Id: paths.h,v 1.27 1999/04/03 00:18:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -48,7 +48,7 @@ extern List *create_or_index_paths(Query *root, RelOptInfo *rel, List *clauses);
  *	  routines to deal with hash keys and clauses
  */
 extern List *group_clauses_by_hashop(List *restrictinfo_list,
-						int inner_relid);
+									 Relids inner_relids);
 
 /*
  * joinutils.h
@@ -70,9 +70,9 @@ extern List *new_join_pathkeys(List *outer_pathkeys,
  *	  routines to deal with merge keys and clauses
  */
 extern List *group_clauses_by_order(List *restrictinfo_list,
-					   int inner_relid);
+									Relids inner_relids);
 extern MergeInfo *match_order_mergeinfo(PathOrder *ordering,
-					  List *mergeinfo_list);
+										List *mergeinfo_list);
 
 /*
  * joinrels.h