Major revision of sort-node handling: push knowledge of query

sort order down into planner, instead of handling it only at the very top
level of the planner.  This fixes many things.  An explicit sort is now
avoided if there is a cheaper alternative (typically an indexscan) not
only for ORDER BY, but also for the internal sort of GROUP BY.  It works
even when there is no other reason (such as a WHERE condition) to consider
the indexscan.  It works for indexes on functions.  It works for indexes
on functions, backwards.  It's just so cool...

CAUTION: I have changed the representation of SortClause nodes, therefore
THIS UPDATE BREAKS STORED RULES.  You will need to initdb.

3 files changed, 19 insertions, 9 deletions

diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index b0ec64c3e32..58da94368c9 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 1.34 1999/08/16 02:17:45 tgl Exp $
+ * $Id: paths.h,v 1.35 1999/08/21 03:49:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -56,11 +56,15 @@ typedef enum
 
 extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
 extern bool pathkeys_contained_in(List *keys1, List *keys2);
-extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys);
+extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
+											bool indexpaths_only);
 extern List *build_index_pathkeys(Query *root, RelOptInfo *rel,
 								  RelOptInfo *index);
 extern List *build_join_pathkeys(List *outer_pathkeys,
 								 List *join_rel_tlist, List *joinclauses);
+extern bool commute_pathkeys(List *pathkeys);
+extern List *make_pathkeys_for_sortclauses(List *sortclauses,
+										   List *tlist);
 extern List *find_mergeclauses_for_pathkeys(List *pathkeys,
 											List *restrictinfos);
 extern List *make_pathkeys_for_mergeclauses(List *mergeclauses,
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 0ba017471d1..38ff367384b 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: planmain.h,v 1.30 1999/08/09 00:56:04 tgl Exp $
+ * $Id: planmain.h,v 1.31 1999/08/21 03:49:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -33,7 +33,7 @@ extern Sort *make_sort(List *tlist, Oid nonameid, Plan *lefttree,
 		  int keycount);
 extern Agg *make_agg(List *tlist, Plan *lefttree);
 extern Group *make_group(List *tlist, bool tuplePerGroup, int ngrp,
-		   AttrNumber *grpColIdx, Sort *lefttree);
+		   AttrNumber *grpColIdx, Plan *lefttree);
 extern Unique *make_unique(List *tlist, Plan *lefttree, char *uniqueAttr);
 
 /*
@@ -54,9 +54,14 @@ extern void replace_tlist_with_subplan_refs(List *tlist,
 								Index subvarno,
 								List *subplanTargetList);
 extern bool set_agg_tlist_references(Agg *aggNode);
+extern List *pull_agg_clause(Node *clause);
 extern void check_having_for_ungrouped_vars(Node *clause,
 								List *groupClause,
 								List *targetList);
+
+/*
+ * prep/prepkeyset.c
+ */
 extern void transformKeySetQuery(Query *origNode);
 
 #endif	 /* PLANMAIN_H */
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index fb08b708352..f0ddb9ac9dc 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: tlist.h,v 1.20 1999/08/16 02:17:45 tgl Exp $
+ * $Id: tlist.h,v 1.21 1999/08/21 03:49:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,16 +21,17 @@ extern void add_var_to_tlist(RelOptInfo *rel, Var *var);
 extern TargetEntry *create_tl_element(Var *var, int resdomno);
 extern List *get_actual_tlist(List *tlist);
 extern Resdom *tlist_member(Var *var, List *tlist);
-extern Resdom *tlist_resdom(List *tlist, Resdom *resnode);
 
 extern TargetEntry *match_varid(Var *test_var, List *tlist);
 extern List *new_unsorted_tlist(List *targetlist);
 extern List *copy_vars(List *target, List *source);
 extern List *flatten_tlist(List *tlist);
-extern List *flatten_tlist_vars(List *full_tlist,
-				   List *flat_tlist);
+extern List *add_to_flat_tlist(List *tlist, List *vars);
+extern List *unflatten_tlist(List *full_tlist,
+							 List *flat_tlist);
 
 extern Var *get_expr(TargetEntry *tle);
-extern Var *get_groupclause_expr(GroupClause *groupClause, List *targetList);
+extern Node *get_sortgroupclause_expr(SortClause *sortClause,
+									  List *targetList);
 
 #endif	 /* TLIST_H */