Create the planner mechanism for optimizing simple MIN and MAX queries

into indexscans on matching indexes.  For the moment, it only handles
int4 and text datatypes; next step is to add a column to pg_aggregate
so that all MIN/MAX aggregates can be handled.  Per my recent proposal.

4 files changed, 16 insertions, 4 deletions

diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 28c44444d70..e5ca24807d0 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.80 2005/03/27 06:29:49 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.81 2005/04/11 23:06:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -38,8 +38,11 @@ extern void debug_print_rel(Query *root, RelOptInfo *rel);
 extern void create_index_paths(Query *root, RelOptInfo *rel);
 extern Path *best_inner_indexscan(Query *root, RelOptInfo *rel,
 					 Relids outer_relids, JoinType jointype);
+extern List *group_clauses_by_indexkey(IndexOptInfo *index);
 extern List *group_clauses_by_indexkey_for_or(IndexOptInfo *index,
 								 Expr *orsubclause);
+extern bool match_index_to_operand(Node *operand, int indexcol,
+					   IndexOptInfo *index);
 extern List *expand_indexqual_conditions(IndexOptInfo *index,
 										 List *clausegroups);
 extern void check_partial_indexes(Query *root, RelOptInfo *rel);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index e76d55ea496..f2a48e77c9e 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.80 2005/03/10 23:21:25 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.81 2005/04/11 23:06:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -24,6 +24,12 @@ extern void query_planner(Query *root, List *tlist, double tuple_fraction,
 			  Path **cheapest_path, Path **sorted_path);
 
 /*
+ * prototypes for plan/planagg.c
+ */
+extern Plan *optimize_minmax_aggregates(Query *root, List *tlist,
+										Path *best_path);
+
+/*
  * prototypes for plan/createplan.c
  */
 extern Plan *create_plan(Query *root, Path *best_path);
diff --git a/src/include/optimizer/subselect.h b/src/include/optimizer/subselect.h
index c07593ad48e..9381321a46f 100644
--- a/src/include/optimizer/subselect.h
+++ b/src/include/optimizer/subselect.h
@@ -5,7 +5,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/subselect.h,v 1.23 2004/12/31 22:03:36 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/subselect.h,v 1.24 2005/04/11 23:06:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -24,5 +24,7 @@ extern Node *convert_IN_to_join(Query *parse, SubLink *sublink);
 extern Node *SS_replace_correlation_vars(Node *expr);
 extern Node *SS_process_sublinks(Node *expr, bool isQual);
 extern void SS_finalize_plan(Plan *plan, List *rtable);
+extern Param *SS_make_initplan_from_plan(Query *root, Plan *plan,
+										 Oid resulttype, int32 resulttypmod);
 
 #endif   /* SUBSELECT_H */
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 845a886ba82..b98b53c60fc 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/lsyscache.h,v 1.96 2005/03/31 22:46:27 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/lsyscache.h,v 1.97 2005/04/11 23:06:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -25,6 +25,7 @@ typedef enum IOFuncSelector
 } IOFuncSelector;
 
 extern bool op_in_opclass(Oid opno, Oid opclass);
+extern int	get_op_opclass_strategy(Oid opno, Oid opclass);
 extern void get_op_opclass_properties(Oid opno, Oid opclass,
 						  int *strategy, Oid *subtype,
 						  bool *recheck);