Some further performance tweaks for planning large inheritance trees that

are mostly excluded by constraints: do the CE test a bit earlier to save
some adjust_appendrel_attrs() work on excluded children, and arrange to
use array indexing rather than rt_fetch() to fetch RTEs in the main body
of the planner.  The latter is something I'd wanted to do for awhile anyway,
but seeing list_nth_cell() as 35% of the runtime gets one's attention.

src/backend/optimizer/path/allpaths.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.162 2007/04/21 06:18:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.163 2007/04/21 21:01:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -39,7 +39,8 @@ int			geqo_threshold;
 
 
 static void set_base_rel_pathlists(PlannerInfo *root);
-static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, Index rti);
+static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
+							 Index rti, RangeTblEntry *rte);
 static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 					   RangeTblEntry *rte);
 static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
@@ -144,7 +145,7 @@ set_base_rel_pathlists(PlannerInfo *root)
 		if (rel->reloptkind != RELOPT_BASEREL)
 			continue;
 
-		set_rel_pathlist(root, rel, rti);
+		set_rel_pathlist(root, rel, rti, root->simple_rte_array[rti]);
 	}
 }
 
@@ -153,10 +154,9 @@ set_base_rel_pathlists(PlannerInfo *root)
  *	  Build access paths for a base relation
  */
 static void
-set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, Index rti)
+set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
+				 Index rti, RangeTblEntry *rte)
 {
-	RangeTblEntry *rte = rt_fetch(rti, root->parse->rtable);
-
 	if (rte->inh)
 	{
 		/* It's an "append relation", process accordingly */
@@ -200,8 +200,11 @@ set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
 	 * If we can prove we don't need to scan the rel via constraint exclusion,
 	 * set up a single dummy path for it.  (Rather than inventing a special
 	 * "dummy" path type, we represent this as an AppendPath with no members.)
+	 * We only need to check for regular baserels; if it's an otherrel, CE
+	 * was already checked in set_append_rel_pathlist().
 	 */
-	if (relation_excluded_by_constraints(rel, rte))
+	if (rel->reloptkind == RELOPT_BASEREL &&
+		relation_excluded_by_constraints(rel, rte))
 	{
 		/* Set dummy size estimates --- we leave attr_widths[] as zeroes */
 		rel->rows = 0;
@@ -294,6 +297,7 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 	{
 		AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
 		int			childRTindex;
+		RangeTblEntry *childRTE;
 		RelOptInfo *childrel;
 		Path	   *childpath;
 		ListCell   *parentvars;
@@ -304,6 +308,7 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 			continue;
 
 		childRTindex = appinfo->child_relid;
+		childRTE = root->simple_rte_array[childRTindex];
 
 		/*
 		 * The child rel's RelOptInfo was already created during
@@ -313,18 +318,29 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 		Assert(childrel->reloptkind == RELOPT_OTHER_MEMBER_REL);
 
 		/*
-		 * Copy the parent's targetlist and quals to the child, with
-		 * appropriate substitution of variables.
+		 * We have to copy the parent's targetlist and quals to the child,
+		 * with appropriate substitution of variables.  However, only the
+		 * baserestrictinfo quals are needed before we can check for
+		 * constraint exclusion; so do that first and then check to see
+		 * if we can disregard this child.
 		 */
-		childrel->reltargetlist = (List *)
-			adjust_appendrel_attrs((Node *) rel->reltargetlist,
-								   appinfo);
 		childrel->baserestrictinfo = (List *)
 			adjust_appendrel_attrs((Node *) rel->baserestrictinfo,
 								   appinfo);
+
+		if (relation_excluded_by_constraints(childrel, childRTE))
+		{
+			/* this child need not be scanned, so just disregard it */
+			continue;
+		}
+
+		/* CE failed, so finish copying targetlist and join quals */
 		childrel->joininfo = (List *)
 			adjust_appendrel_attrs((Node *) rel->joininfo,
 								   appinfo);
+		childrel->reltargetlist = (List *)
+			adjust_appendrel_attrs((Node *) rel->reltargetlist,
+								   appinfo);
 
 		/*
 		 * We have to make child entries in the EquivalenceClass data
@@ -353,12 +369,9 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 		 * It's possible that the child is itself an appendrel, in which case
 		 * we can "cut out the middleman" and just add its child paths to our
 		 * own list.  (We don't try to do this earlier because we need to
-		 * apply both levels of transformation to the quals.) This test also
-		 * handles the case where the child rel need not be scanned because of
-		 * constraint exclusion: it'll have an Append path with no subpaths,
-		 * and will vanish from our list.
+		 * apply both levels of transformation to the quals.)
 		 */
-		set_rel_pathlist(root, childrel, childRTindex);
+		set_rel_pathlist(root, childrel, childRTindex, childRTE);
 
 		childpath = childrel->cheapest_total_path;
 		if (IsA(childpath, AppendPath))

src/backend/optimizer/path/clausesel.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.84 2007/02/19 07:03:28 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.85 2007/04/21 21:01:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -500,7 +500,7 @@ clause_selectivity(PlannerInfo *root,
 		if (var->varlevelsup == 0 &&
 			(varRelid == 0 || varRelid == (int) var->varno))
 		{
-			RangeTblEntry *rte = rt_fetch(var->varno, root->parse->rtable);
+			RangeTblEntry *rte = planner_rt_fetch(var->varno, root);
 
 			if (rte->rtekind == RTE_SUBQUERY)
 			{

src/backend/optimizer/path/costsize.c

@@ -54,7 +54,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.180 2007/04/21 02:41:13 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.181 2007/04/21 21:01:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -856,7 +856,7 @@ cost_functionscan(Path *path, PlannerInfo *root, RelOptInfo *baserel)
 
 	/* Should only be applied to base relations that are functions */
 	Assert(baserel->relid > 0);
-	rte = rt_fetch(baserel->relid, root->parse->rtable);
+	rte = planner_rt_fetch(baserel->relid, root);
 	Assert(rte->rtekind == RTE_FUNCTION);
 
 	/* Estimate costs of executing the function expression */
@@ -2297,7 +2297,7 @@ set_function_size_estimates(PlannerInfo *root, RelOptInfo *rel)
 
 	/* Should only be applied to base relations that are functions */
 	Assert(rel->relid > 0);
-	rte = rt_fetch(rel->relid, root->parse->rtable);
+	rte = planner_rt_fetch(rel->relid, root);
 	Assert(rte->rtekind == RTE_FUNCTION);
 
 	/* Estimate number of rows the function itself will return */
@@ -2323,7 +2323,7 @@ set_values_size_estimates(PlannerInfo *root, RelOptInfo *rel)
 
 	/* Should only be applied to base relations that are values lists */
 	Assert(rel->relid > 0);
-	rte = rt_fetch(rel->relid, root->parse->rtable);
+	rte = planner_rt_fetch(rel->relid, root);
 	Assert(rte->rtekind == RTE_VALUES);
 
 	/*

src/backend/optimizer/plan/createplan.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.228 2007/04/06 22:33:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.229 2007/04/21 21:01:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1353,7 +1353,7 @@ create_functionscan_plan(PlannerInfo *root, Path *best_path,
 
 	/* it should be a function base rel... */
 	Assert(scan_relid > 0);
-	rte = rt_fetch(scan_relid, root->parse->rtable);
+	rte = planner_rt_fetch(scan_relid, root);
 	Assert(rte->rtekind == RTE_FUNCTION);
 
 	/* Sort clauses into best execution order */
@@ -1388,7 +1388,7 @@ create_valuesscan_plan(PlannerInfo *root, Path *best_path,
 
 	/* it should be a values base rel... */
 	Assert(scan_relid > 0);
-	rte = rt_fetch(scan_relid, root->parse->rtable);
+	rte = planner_rt_fetch(scan_relid, root);
 	Assert(rte->rtekind == RTE_VALUES);
 
 	/* Sort clauses into best execution order */

src/backend/optimizer/plan/planagg.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.30 2007/03/17 00:11:04 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.31 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -116,7 +116,7 @@ optimize_minmax_aggregates(PlannerInfo *root, List *tlist, Path *best_path)
 	if (!IsA(jtnode, RangeTblRef))
 		return NULL;
 	rtr = (RangeTblRef *) jtnode;
-	rte = rt_fetch(rtr->rtindex, parse->rtable);
+	rte = planner_rt_fetch(rtr->rtindex, root);
 	if (rte->rtekind != RTE_RELATION || rte->inh)
 		return NULL;
 	rel = find_base_rel(root, rtr->rtindex);

src/backend/optimizer/plan/planmain.c

@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.99 2007/01/20 20:45:39 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.100 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,6 +86,7 @@ query_planner(PlannerInfo *root, List *tlist, double tuple_fraction,
 	Path	   *cheapestpath;
 	Path	   *sortedpath;
 	Index		rti;
+	ListCell   *lc;
 	double		total_pages;
 
 	/* Make tuple_fraction accessible to lower-level routines */
@@ -123,6 +124,20 @@ query_planner(PlannerInfo *root, List *tlist, double tuple_fraction,
 	root->full_join_clauses = NIL;
 	root->oj_info_list = NIL;
 
+	/*
+	 * Make a flattened version of the rangetable for faster access (this
+	 * is OK because the rangetable won't change any more).
+	 */
+	root->simple_rte_array = (RangeTblEntry **)
+		palloc0(root->simple_rel_array_size * sizeof(RangeTblEntry *));
+	rti = 1;
+	foreach(lc, parse->rtable)
+	{
+		RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
+
+		root->simple_rte_array[rti++] = rte;
+	}
+
 	/*
 	 * Construct RelOptInfo nodes for all base relations in query, and
 	 * indirectly for all appendrel member relations ("other rels").  This

src/backend/optimizer/util/pathnode.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.138 2007/02/06 02:59:12 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.139 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -800,7 +800,7 @@ create_unique_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath)
 	 */
 	if (sub_targetlist && rel->rtekind == RTE_SUBQUERY)
 	{
-		RangeTblEntry *rte = rt_fetch(rel->relid, root->parse->rtable);
+		RangeTblEntry *rte = planner_rt_fetch(rel->relid, root);
 		List	   *sub_tlist_colnos;
 
 		sub_tlist_colnos = translate_sub_tlist(sub_targetlist, rel->relid);

src/backend/optimizer/util/plancat.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.133 2007/04/06 22:33:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/plancat.c,v 1.134 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -497,6 +497,9 @@ get_relation_constraints(Oid relationObjectId, RelOptInfo *rel)
  * Detect whether the relation need not be scanned because it has either
  * self-inconsistent restrictions, or restrictions inconsistent with the
  * relation's CHECK constraints.
+ *
+ * Note: this examines only rel->relid and rel->baserestrictinfo; therefore
+ * it can be called before filling in other fields of the RelOptInfo.
  */
 bool
 relation_excluded_by_constraints(RelOptInfo *rel, RangeTblEntry *rte)
@@ -595,7 +598,7 @@ build_physical_tlist(PlannerInfo *root, RelOptInfo *rel)
 {
 	List	   *tlist = NIL;
 	Index		varno = rel->relid;
-	RangeTblEntry *rte = rt_fetch(varno, root->parse->rtable);
+	RangeTblEntry *rte = planner_rt_fetch(varno, root);
 	Relation	relation;
 	Query	   *subquery;
 	Var		   *var;

src/backend/optimizer/util/relnode.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/relnode.c,v 1.86 2007/02/22 22:00:25 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/relnode.c,v 1.87 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -56,15 +56,15 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind)
 	RelOptInfo *rel;
 	RangeTblEntry *rte;
 
-	/* Fetch RTE for relation */
-	Assert(relid > 0 && relid <= list_length(root->parse->rtable));
-	rte = rt_fetch(relid, root->parse->rtable);
-
 	/* Rel should not exist already */
-	Assert(relid < root->simple_rel_array_size);
+	Assert(relid > 0 && relid < root->simple_rel_array_size);
 	if (root->simple_rel_array[relid] != NULL)
 		elog(ERROR, "rel %d already exists", relid);
 
+	/* Fetch RTE for relation */
+	rte = root->simple_rte_array[relid];
+	Assert(rte != NULL);
+
 	rel = makeNode(RelOptInfo);
 	rel->reloptkind = reloptkind;
 	rel->relids = bms_make_singleton(relid);

src/backend/utils/adt/selfuncs.c

@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.232 2007/04/06 22:33:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.233 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3487,7 +3487,7 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
 		vardata->atttype = var->vartype;
 		vardata->atttypmod = var->vartypmod;
 
-		rte = rt_fetch(var->varno, root->parse->rtable);
+		rte = root->simple_rte_array[var->varno];
 
 		if (rte->inh)
 		{

src/include/nodes/relation.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.140 2007/04/06 22:33:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.141 2007/04/21 21:01:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -108,6 +108,14 @@ typedef struct PlannerInfo
 	struct RelOptInfo **simple_rel_array;		/* All 1-rel RelOptInfos */
 	int			simple_rel_array_size;	/* allocated size of array */
 
+	/*
+	 * simple_rte_array is the same length as simple_rel_array and holds
+	 * pointers to the associated rangetable entries.  This lets us avoid
+	 * rt_fetch(), which can be a bit slow once large inheritance sets have
+	 * been expanded.
+	 */
+	RangeTblEntry **simple_rte_array;			/* rangetable as an array */
+
 	/*
 	 * join_rel_list is a list of all join-relation RelOptInfos we have
 	 * considered in this planning run.  For small problems we just scan the
@@ -167,6 +175,16 @@ typedef struct PlannerInfo
 } PlannerInfo;
 
 
+/*
+ * In places where it's known that simple_rte_array[] must have been prepared
+ * already, we just index into it to fetch RTEs.  In code that might be
+ * executed before or after entering query_planner(), use this macro.
+ */
+#define planner_rt_fetch(rti, root) \
+	((root)->simple_rte_array ? (root)->simple_rte_array[rti] : \
+	 rt_fetch(rti, (root)->parse->rtable))
+
+
 /*----------
  * RelOptInfo
  *		Per-relation information for planning/optimization