Revise cost_qual_eval() to compute both startup (one-time) and per-tuple

costs for expression evaluation, not only per-tuple cost as before.
This extension is needed in order to deal realistically with hashed or
materialized sub-selects.

doc/src/sgml/indexcost.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/Attic/indexcost.sgml,v 2.12 2002/08/22 00:01:40 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/Attic/indexcost.sgml,v 2.13 2003/01/12 22:35:29 tgl Exp $
 -->
 
  <chapter id="indexcost">
@@ -237,9 +237,10 @@ amcostestimate (Query *root,
      * Also, we charge for evaluation of the indexquals at each index tuple.
      * All the costs are assumed to be paid incrementally during the scan.
      */
-    *indexStartupCost = 0;
+    cost_qual_eval(&index_qual_cost, indexQuals);
+    *indexStartupCost = index_qual_cost.startup;
     *indexTotalCost = numIndexPages +
-        (cpu_index_tuple_cost + cost_qual_eval(indexQuals)) * numIndexTuples;
+        (cpu_index_tuple_cost + index_qual_cost.per_tuple) * numIndexTuples;
      </programlisting>
     </para>
    </step>

src/backend/optimizer/plan/initsplan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.79 2002/12/17 01:18:25 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.80 2003/01/12 22:35:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -396,7 +396,7 @@ distribute_qual_to_rels(Query *root, Node *clause,
 
 	restrictinfo->clause = (Expr *) clause;
 	restrictinfo->subclauseindices = NIL;
-	restrictinfo->eval_cost = -1;		/* not computed until needed */
+	restrictinfo->eval_cost.startup = -1; /* not computed until needed */
 	restrictinfo->this_selec = -1;		/* not computed until needed */
 	restrictinfo->mergejoinoperator = InvalidOid;
 	restrictinfo->left_sortop = InvalidOid;

src/backend/optimizer/prep/prepunion.c

@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.84 2003/01/05 00:56:40 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.85 2003/01/12 22:35:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -853,7 +853,7 @@ adjust_inherited_attrs_mutator(Node *node,
 			adjust_inherited_attrs_mutator((Node *) oldinfo->clause, context);
 
 		newinfo->subclauseindices = NIL;
-		newinfo->eval_cost = -1;	/* reset these too */
+		newinfo->eval_cost.startup = -1; /* reset these too */
 		newinfo->this_selec = -1;
 		newinfo->left_pathkey = NIL;	/* and these */
 		newinfo->right_pathkey = NIL;

src/backend/optimizer/util/relnode.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.41 2002/11/24 21:52:14 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.42 2003/01/12 22:35:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -149,7 +149,8 @@ make_base_rel(Query *root, int relid)
 	rel->joinrti = 0;
 	rel->joinrteids = NIL;
 	rel->baserestrictinfo = NIL;
-	rel->baserestrictcost = 0;
+	rel->baserestrictcost.startup = 0;
+	rel->baserestrictcost.per_tuple = 0;
 	rel->outerjoinset = NIL;
 	rel->joininfo = NIL;
 	rel->index_outer_relids = NIL;
@@ -363,7 +364,8 @@ build_join_rel(Query *root,
 	joinrel->joinrteids = nconc(listCopy(outer_rel->joinrteids),
 								inner_rel->joinrteids);
 	joinrel->baserestrictinfo = NIL;
-	joinrel->baserestrictcost = 0;
+	joinrel->baserestrictcost.startup = 0;
+	joinrel->baserestrictcost.per_tuple = 0;
 	joinrel->outerjoinset = NIL;
 	joinrel->joininfo = NIL;
 	joinrel->index_outer_relids = NIL;

src/backend/utils/adt/selfuncs.c

@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.124 2002/12/17 01:18:35 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.125 2003/01/12 22:35:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3757,6 +3757,7 @@ genericcostestimate(Query *root, RelOptInfo *rel,
 {
 	double		numIndexTuples;
 	double		numIndexPages;
+	QualCost	index_qual_cost;
 	List	   *selectivityQuals = indexQuals;
 
 	/*
@@ -3826,9 +3827,10 @@ genericcostestimate(Query *root, RelOptInfo *rel,
 	 * tuple. All the costs are assumed to be paid incrementally during
 	 * the scan.
 	 */
-	*indexStartupCost = 0;
+	cost_qual_eval(&index_qual_cost, indexQuals);
+	*indexStartupCost = index_qual_cost.startup;
 	*indexTotalCost = numIndexPages +
-		(cpu_index_tuple_cost + cost_qual_eval(indexQuals)) * numIndexTuples;
+		(cpu_index_tuple_cost + index_qual_cost.per_tuple) * numIndexTuples;
 
 	/*
 	 * Generic assumption about index correlation: there isn't any.

src/include/nodes/relation.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: relation.h,v 1.74 2002/12/12 15:49:40 tgl Exp $
+ * $Id: relation.h,v 1.75 2003/01/12 22:35:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -35,6 +35,16 @@ typedef enum CostSelector
 	STARTUP_COST, TOTAL_COST
 } CostSelector;
 
+/*
+ * The cost estimate produced by cost_qual_eval() includes both a one-time
+ * (startup) cost, and a per-tuple cost.
+ */
+typedef struct QualCost
+{
+	Cost		startup;		/* one-time cost */
+	Cost		per_tuple;		/* per-evaluation cost */
+} QualCost;
+
 /*----------
  * RelOptInfo
  *		Per-relation information for planning/optimization
@@ -199,7 +209,7 @@ typedef struct RelOptInfo
 	/* used by various scans and joins: */
 	List	   *baserestrictinfo;		/* RestrictInfo structures (if
 										 * base rel) */
-	Cost		baserestrictcost;		/* cost of evaluating the above */
+	QualCost	baserestrictcost;		/* cost of evaluating the above */
 	Relids		outerjoinset;	/* integer list of base relids */
 	List	   *joininfo;		/* JoinInfo structures */
 
@@ -570,7 +580,7 @@ typedef struct RestrictInfo
 	/* subclauseindices is a List of Lists of IndexOptInfos */
 
 	/* cache space for costs (currently only used for join clauses) */
-	Cost		eval_cost;		/* eval cost of clause; -1 if not yet set */
+	QualCost	eval_cost;		/* eval cost of clause; -1 if not yet set */
 	Selectivity this_selec;		/* selectivity; -1 if not yet set */
 
 	/* valid if clause is mergejoinable, else InvalidOid: */

src/include/optimizer/cost.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: cost.h,v 1.49 2002/11/30 05:21:03 tgl Exp $
+ * $Id: cost.h,v 1.50 2003/01/12 22:35:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -83,7 +83,7 @@ extern void cost_hashjoin(Path *path, Query *root,
 			  Path *outer_path, Path *inner_path,
 			  List *restrictlist,
 			  List *hashclauses);
-extern Cost cost_qual_eval(List *quals);
+extern void cost_qual_eval(QualCost *cost, List *quals);
 extern void set_baserel_size_estimates(Query *root, RelOptInfo *rel);
 extern void set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
 						   RelOptInfo *outer_rel,