X-Git-Url: https://granicus.if.org/sourcecode?a=blobdiff_plain;f=src%2Fbackend%2Foptimizer%2Fplan%2Fplanner.c;h=b542fef61e26a697c1fbd44dec2be43147456b70;hb=addc42c339208d6a7a1d652fbf388e8aea7f80b9;hp=2b46b4b740102b229051a26c17071cb993422366;hpb=056467ec6bcbd81a9d1480af8d641946a5ef1bff;p=postgresql

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 2b46b4b740..b542fef61e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -3,12 +3,12 @@
  * planner.c
  *	  The query optimizer external interface.
  *
- * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.147 2003/02/15 20:12:40 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.184 2005/04/11 23:06:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -19,6 +19,8 @@
 
 #include "catalog/pg_operator.h"
 #include "catalog/pg_type.h"
+#include "executor/executor.h"
+#include "executor/nodeAgg.h"
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #ifdef OPTIMIZER_DEBUG
@@ -34,7 +36,6 @@
 #include "optimizer/subselect.h"
 #include "optimizer/tlist.h"
 #include "optimizer/var.h"
-#include "parser/analyze.h"
 #include "parser/parsetree.h"
 #include "parser/parse_expr.h"
 #include "parser/parse_oper.h"
@@ -42,28 +43,32 @@
 #include "utils/syscache.h"
 
 
+ParamListInfo PlannerBoundParamList = NULL;		/* current boundParams */
+
+
 /* Expression kind codes for preprocess_expression */
 #define EXPRKIND_QUAL	0
-#define EXPRKIND_TARGET	1
-#define EXPRKIND_RTFUNC	2
-#define EXPRKIND_ININFO	3
+#define EXPRKIND_TARGET 1
+#define EXPRKIND_RTFUNC 2
+#define EXPRKIND_LIMIT	3
+#define EXPRKIND_ININFO 4
 
 
 static Node *preprocess_expression(Query *parse, Node *expr, int kind);
 static void preprocess_qual_conditions(Query *parse, Node *jtnode);
 static Plan *inheritance_planner(Query *parse, List *inheritlist);
 static Plan *grouping_planner(Query *parse, double tuple_fraction);
+static bool choose_hashed_grouping(Query *parse, double tuple_fraction,
+					   Path *cheapest_path, Path *sorted_path,
+					   List *sort_pathkeys, List *group_pathkeys,
+					   double dNumGroups, AggClauseCounts *agg_counts);
 static bool hash_safe_grouping(Query *parse);
 static List *make_subplanTargetList(Query *parse, List *tlist,
 					   AttrNumber **groupColIdx, bool *need_tlist_eval);
 static void locate_grouping_columns(Query *parse,
-									List *tlist,
-									List *sub_tlist,
-									AttrNumber *groupColIdx);
-static Plan *make_groupsortplan(Query *parse,
-								List *groupClause,
-								AttrNumber *grpColIdx,
-								Plan *subplan);
+						List *tlist,
+						List *sub_tlist,
+						AttrNumber *groupColIdx);
 static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
 
 
@@ -73,19 +78,25 @@ static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
  *
  *****************************************************************************/
 Plan *
-planner(Query *parse)
+planner(Query *parse, bool isCursor, int cursorOptions,
+		ParamListInfo boundParams)
 {
+	double		tuple_fraction;
 	Plan	   *result_plan;
 	Index		save_PlannerQueryLevel;
-	List	   *save_PlannerParamVar;
+	List	   *save_PlannerParamList;
+	ParamListInfo save_PlannerBoundParamList;
 
 	/*
 	 * The planner can be called recursively (an example is when
 	 * eval_const_expressions tries to pre-evaluate an SQL function). So,
 	 * these global state variables must be saved and restored.
 	 *
-	 * These vars cannot be moved into the Query structure since their whole
-	 * purpose is communication across multiple sub-Queries.
+	 * Query level and the param list cannot be moved into the Query
+	 * structure since their whole purpose is communication across
+	 * multiple sub-Queries. Also, boundParams is explicitly info from
+	 * outside the Query, and so is likewise better handled as a global
+	 * variable.
 	 *
 	 * Note we do NOT save and restore PlannerPlanId: it exists to assign
 	 * unique IDs to SubPlan nodes, and we want those IDs to be unique for
@@ -93,26 +104,56 @@ planner(Query *parse)
 	 * subquery_planner, not here.
 	 */
 	save_PlannerQueryLevel = PlannerQueryLevel;
-	save_PlannerParamVar = PlannerParamVar;
+	save_PlannerParamList = PlannerParamList;
+	save_PlannerBoundParamList = PlannerBoundParamList;
 
 	/* Initialize state for handling outer-level references and params */
 	PlannerQueryLevel = 0;		/* will be 1 in top-level subquery_planner */
-	PlannerParamVar = NIL;
+	PlannerParamList = NIL;
+	PlannerBoundParamList = boundParams;
+
+	/* Determine what fraction of the plan is likely to be scanned */
+	if (isCursor)
+	{
+		/*
+		 * We have no real idea how many tuples the user will ultimately
+		 * FETCH from a cursor, but it seems a good bet that he doesn't
+		 * want 'em all.  Optimize for 10% retrieval (you gotta better
+		 * number?	Should this be a SETtable parameter?)
+		 */
+		tuple_fraction = 0.10;
+	}
+	else
+	{
+		/* Default assumption is we need all the tuples */
+		tuple_fraction = 0.0;
+	}
 
 	/* primary planning entry point (may recurse for subqueries) */
-	result_plan = subquery_planner(parse, -1.0 /* default case */ );
+	result_plan = subquery_planner(parse, tuple_fraction);
 
 	Assert(PlannerQueryLevel == 0);
 
+	/*
+	 * If creating a plan for a scrollable cursor, make sure it can run
+	 * backwards on demand.  Add a Material node at the top at need.
+	 */
+	if (isCursor && (cursorOptions & CURSOR_OPT_SCROLL))
+	{
+		if (!ExecSupportsBackwardScan(result_plan))
+			result_plan = materialize_finished_plan(result_plan);
+	}
+
 	/* executor wants to know total number of Params used overall */
-	result_plan->nParamExec = length(PlannerParamVar);
+	result_plan->nParamExec = list_length(PlannerParamList);
 
 	/* final cleanup of the plan */
 	set_plan_references(result_plan, parse->rtable);
 
 	/* restore state for outer planner, if any */
 	PlannerQueryLevel = save_PlannerQueryLevel;
-	PlannerParamVar = save_PlannerParamVar;
+	PlannerParamList = save_PlannerParamList;
+	PlannerBoundParamList = save_PlannerBoundParamList;
 
 	return result_plan;
 }
@@ -148,6 +189,7 @@ subquery_planner(Query *parse, double tuple_fraction)
 	Plan	   *plan;
 	List	   *newHaving;
 	List	   *lst;
+	ListCell   *l;
 
 	/* Set up for a new level of subquery */
 	PlannerQueryLevel++;
@@ -155,14 +197,14 @@ subquery_planner(Query *parse, double tuple_fraction)
 
 	/*
 	 * Look for IN clauses at the top level of WHERE, and transform them
-	 * into joins.  Note that this step only handles IN clauses originally
-	 * at top level of WHERE; if we pull up any subqueries in the next step,
-	 * their INs are processed just before pulling them up.
+	 * into joins.	Note that this step only handles IN clauses originally
+	 * at top level of WHERE; if we pull up any subqueries in the next
+	 * step, their INs are processed just before pulling them up.
 	 */
 	parse->in_info_list = NIL;
 	if (parse->hasSubLinks)
 		parse->jointree->quals = pull_up_IN_clauses(parse,
-													parse->jointree->quals);
+												 parse->jointree->quals);
 
 	/*
 	 * Check to see if any subqueries in the rangetable can be merged into
@@ -172,16 +214,17 @@ subquery_planner(Query *parse, double tuple_fraction)
 		pull_up_subqueries(parse, (Node *) parse->jointree, false);
 
 	/*
-	 * Detect whether any rangetable entries are RTE_JOIN kind; if not,
-	 * we can avoid the expense of doing flatten_join_alias_vars().  Also
-	 * check for outer joins --- if none, we can skip reduce_outer_joins().
-	 * This must be done after we have done pull_up_subqueries, of course.
+	 * Detect whether any rangetable entries are RTE_JOIN kind; if not, we
+	 * can avoid the expense of doing flatten_join_alias_vars().  Also
+	 * check for outer joins --- if none, we can skip
+	 * reduce_outer_joins(). This must be done after we have done
+	 * pull_up_subqueries, of course.
 	 */
 	parse->hasJoinRTEs = false;
 	hasOuterJoins = false;
-	foreach(lst, parse->rtable)
+	foreach(l, parse->rtable)
 	{
-		RangeTblEntry *rte = (RangeTblEntry *) lfirst(lst);
+		RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
 
 		if (rte->rtekind == RTE_JOIN)
 		{
@@ -195,6 +238,13 @@ subquery_planner(Query *parse, double tuple_fraction)
 		}
 	}
 
+	/*
+	 * Set hasHavingQual to remember if HAVING clause is present.  Needed
+	 * because preprocess_expression will reduce a constant-true condition
+	 * to an empty qual list ... but "HAVING TRUE" is not a semantic no-op.
+	 */
+	parse->hasHavingQual = (parse->havingQual != NULL);
+
 	/*
 	 * Do expression preprocessing on targetlist and quals.
 	 */
@@ -207,14 +257,19 @@ subquery_planner(Query *parse, double tuple_fraction)
 	parse->havingQual = preprocess_expression(parse, parse->havingQual,
 											  EXPRKIND_QUAL);
 
+	parse->limitOffset = preprocess_expression(parse, parse->limitOffset,
+											   EXPRKIND_LIMIT);
+	parse->limitCount = preprocess_expression(parse, parse->limitCount,
+											  EXPRKIND_LIMIT);
+
 	parse->in_info_list = (List *)
 		preprocess_expression(parse, (Node *) parse->in_info_list,
 							  EXPRKIND_ININFO);
 
 	/* Also need to preprocess expressions for function RTEs */
-	foreach(lst, parse->rtable)
+	foreach(l, parse->rtable)
 	{
-		RangeTblEntry *rte = (RangeTblEntry *) lfirst(lst);
+		RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
 
 		if (rte->rtekind == RTE_FUNCTION)
 			rte->funcexpr = preprocess_expression(parse, rte->funcexpr,
@@ -222,50 +277,74 @@ subquery_planner(Query *parse, double tuple_fraction)
 	}
 
 	/*
-	 * A HAVING clause without aggregates is equivalent to a WHERE clause
-	 * (except it can only refer to grouped fields).  Transfer any
-	 * agg-free clauses of the HAVING qual into WHERE.	This may seem like
-	 * wasting cycles to cater to stupidly-written queries, but there are
-	 * other reasons for doing it.	Firstly, if the query contains no aggs
-	 * at all, then we aren't going to generate an Agg plan node, and so
-	 * there'll be no place to execute HAVING conditions; without this
-	 * transfer, we'd lose the HAVING condition entirely, which is wrong.
-	 * Secondly, when we push down a qual condition into a sub-query, it's
-	 * easiest to push the qual into HAVING always, in case it contains
-	 * aggs, and then let this code sort it out.
+	 * In some cases we may want to transfer a HAVING clause into WHERE.
+	 * We cannot do so if the HAVING clause contains aggregates (obviously)
+	 * or volatile functions (since a HAVING clause is supposed to be executed
+	 * only once per group).  Also, it may be that the clause is so expensive
+	 * to execute that we're better off doing it only once per group, despite
+	 * the loss of selectivity.  This is hard to estimate short of doing the
+	 * entire planning process twice, so we use a heuristic: clauses
+	 * containing subplans are left in HAVING.  Otherwise, we move or copy
+	 * the HAVING clause into WHERE, in hopes of eliminating tuples before
+	 * aggregation instead of after.
+	 *
+	 * If the query has explicit grouping then we can simply move such a
+	 * clause into WHERE; any group that fails the clause will not be
+	 * in the output because none of its tuples will reach the grouping
+	 * or aggregation stage.  Otherwise we must have a degenerate
+	 * (variable-free) HAVING clause, which we put in WHERE so that
+	 * query_planner() can use it in a gating Result node, but also keep
+	 * in HAVING to ensure that we don't emit a bogus aggregated row.
+	 * (This could be done better, but it seems not worth optimizing.)
 	 *
 	 * Note that both havingQual and parse->jointree->quals are in
 	 * implicitly-ANDed-list form at this point, even though they are
-	 * declared as Node *.	Also note that contain_agg_clause does not
-	 * recurse into sub-selects, which is exactly what we need here.
+	 * declared as Node *.
 	 */
 	newHaving = NIL;
-	foreach(lst, (List *) parse->havingQual)
+	foreach(l, (List *) parse->havingQual)
 	{
-		Node	   *havingclause = (Node *) lfirst(lst);
+		Node	   *havingclause = (Node *) lfirst(l);
 
-		if (contain_agg_clause(havingclause))
+		if (contain_agg_clause(havingclause) ||
+			contain_volatile_functions(havingclause) ||
+			contain_subplans(havingclause))
+		{
+			/* keep it in HAVING */
 			newHaving = lappend(newHaving, havingclause);
-		else
+		}
+		else if (parse->groupClause)
+		{
+			/* move it to WHERE */
 			parse->jointree->quals = (Node *)
 				lappend((List *) parse->jointree->quals, havingclause);
+		}
+		else
+		{
+			/* put a copy in WHERE, keep it in HAVING */
+			parse->jointree->quals = (Node *)
+				lappend((List *) parse->jointree->quals,
+						copyObject(havingclause));
+			newHaving = lappend(newHaving, havingclause);
+		}
 	}
 	parse->havingQual = (Node *) newHaving;
 
 	/*
-	 * If we have any outer joins, try to reduce them to plain inner joins.
-	 * This step is most easily done after we've done expression preprocessing.
+	 * If we have any outer joins, try to reduce them to plain inner
+	 * joins. This step is most easily done after we've done expression
+	 * preprocessing.
 	 */
 	if (hasOuterJoins)
 		reduce_outer_joins(parse);
 
 	/*
-	 * See if we can simplify the jointree; opportunities for this may come
-	 * from having pulled up subqueries, or from flattening explicit JOIN
-	 * syntax.  We must do this after flattening JOIN alias variables, since
-	 * eliminating explicit JOIN nodes from the jointree will cause
-	 * get_relids_for_join() to fail.  But it should happen after
-	 * reduce_outer_joins, anyway.
+	 * See if we can simplify the jointree; opportunities for this may
+	 * come from having pulled up subqueries, or from flattening explicit
+	 * JOIN syntax.  We must do this after flattening JOIN alias
+	 * variables, since eliminating explicit JOIN nodes from the jointree
+	 * will cause get_relids_for_join() to fail.  But it should happen
+	 * after reduce_outer_joins, anyway.
 	 */
 	parse->jointree = (FromExpr *)
 		simplify_jointree(parse, (Node *) parse->jointree);
@@ -276,48 +355,19 @@ subquery_planner(Query *parse, double tuple_fraction)
 	 * grouping_planner.
 	 */
 	if (parse->resultRelation &&
-	 (lst = expand_inherted_rtentry(parse, parse->resultRelation, false))
-		!= NIL)
+		(lst = expand_inherited_rtentry(parse, parse->resultRelation)) != NIL)
 		plan = inheritance_planner(parse, lst);
 	else
 		plan = grouping_planner(parse, tuple_fraction);
 
 	/*
 	 * If any subplans were generated, or if we're inside a subplan, build
-	 * initPlan list and extParam/allParam sets for plan nodes.
+	 * initPlan list and extParam/allParam sets for plan nodes, and attach
+	 * the initPlans to the top plan node.
 	 */
 	if (PlannerPlanId != saved_planid || PlannerQueryLevel > 1)
-	{
-		Cost	initplan_cost = 0;
-
-		/* Prepare extParam/allParam sets for all nodes in tree */
 		SS_finalize_plan(plan, parse->rtable);
 
-		/*
-		 * SS_finalize_plan doesn't handle initPlans, so we have to manually
-		 * attach them to the topmost plan node, and add their extParams to
-		 * the topmost node's, too.
-		 *
-		 * We also add the total_cost of each initPlan to the startup cost
-		 * of the top node.  This is a conservative overestimate, since in
-		 * fact each initPlan might be executed later than plan startup, or
-		 * even not at all.
-		 */
-		plan->initPlan = PlannerInitPlan;
-
-		foreach(lst, plan->initPlan)
-		{
-			SubPlan	   *initplan = (SubPlan *) lfirst(lst);
-
-			plan->extParam = bms_add_members(plan->extParam,
-											 initplan->plan->extParam);
-			initplan_cost += initplan->plan->total_cost;
-		}
-
-		plan->startup_cost += initplan_cost;
-		plan->total_cost += initplan_cost;
-	}
-
 	/* Return to outer subquery context */
 	PlannerQueryLevel--;
 	PlannerInitPlan = saved_initplan;
@@ -338,7 +388,8 @@ preprocess_expression(Query *parse, Node *expr, int kind)
 	/*
 	 * If the query has any join RTEs, replace join alias variables with
 	 * base-relation variables. We must do this before sublink processing,
-	 * else sublinks expanded out from join aliases wouldn't get processed.
+	 * else sublinks expanded out from join aliases wouldn't get
+	 * processed.
 	 */
 	if (parse->hasJoinRTEs)
 		expr = flatten_join_alias_vars(parse, expr);
@@ -346,21 +397,19 @@ preprocess_expression(Query *parse, Node *expr, int kind)
 	/*
 	 * Simplify constant expressions.
 	 *
-	 * Note that at this point quals have not yet been converted to
-	 * implicit-AND form, so we can apply eval_const_expressions directly.
+	 * Note: this also flattens nested AND and OR expressions into N-argument
+	 * form.  All processing of a qual expression after this point must be
+	 * careful to maintain AND/OR flatness --- that is, do not generate a tree
+	 * with AND directly under AND, nor OR directly under OR.
 	 */
 	expr = eval_const_expressions(expr);
 
 	/*
-	 * If it's a qual or havingQual, canonicalize it, and convert it to
-	 * implicit-AND format.
-	 *
-	 * XXX Is there any value in re-applying eval_const_expressions after
-	 * canonicalize_qual?
+	 * If it's a qual or havingQual, canonicalize it.
 	 */
 	if (kind == EXPRKIND_QUAL)
 	{
-		expr = (Node *) canonicalize_qual((Expr *) expr, true);
+		expr = (Node *) canonicalize_qual((Expr *) expr);
 
 #ifdef OPTIMIZER_DEBUG
 		printf("After canonicalize_qual()\n");
@@ -372,10 +421,24 @@ preprocess_expression(Query *parse, Node *expr, int kind)
 	if (parse->hasSubLinks)
 		expr = SS_process_sublinks(expr, (kind == EXPRKIND_QUAL));
 
+	/*
+	 * XXX do not insert anything here unless you have grokked the
+	 * comments in SS_replace_correlation_vars ...
+	 */
+
 	/* Replace uplevel vars with Param nodes */
 	if (PlannerQueryLevel > 1)
 		expr = SS_replace_correlation_vars(expr);
 
+	/*
+	 * If it's a qual or havingQual, convert it to implicit-AND format.
+	 * (We don't want to do this before eval_const_expressions, since the
+	 * latter would be unable to simplify a top-level AND correctly. Also,
+	 * SS_process_sublinks expects explicit-AND format.)
+	 */
+	if (kind == EXPRKIND_QUAL)
+		expr = (Node *) make_ands_implicit((Expr *) expr);
+
 	return expr;
 }
 
@@ -396,7 +459,7 @@ preprocess_qual_conditions(Query *parse, Node *jtnode)
 	else if (IsA(jtnode, FromExpr))
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
-		List	   *l;
+		ListCell   *l;
 
 		foreach(l, f->fromlist)
 			preprocess_qual_conditions(parse, lfirst(l));
@@ -413,8 +476,8 @@ preprocess_qual_conditions(Query *parse, Node *jtnode)
 		j->quals = preprocess_expression(parse, j->quals, EXPRKIND_QUAL);
 	}
 	else
-		elog(ERROR, "preprocess_qual_conditions: unexpected node type %d",
-			 nodeTag(jtnode));
+		elog(ERROR, "unrecognized node type: %d",
+			 (int) nodeTag(jtnode));
 }
 
 /*--------------------
@@ -443,13 +506,14 @@ inheritance_planner(Query *parse, List *inheritlist)
 {
 	int			parentRTindex = parse->resultRelation;
 	Oid			parentOID = getrelid(parentRTindex, parse->rtable);
+	int			mainrtlength = list_length(parse->rtable);
 	List	   *subplans = NIL;
 	List	   *tlist = NIL;
-	List	   *l;
+	ListCell   *l;
 
 	foreach(l, inheritlist)
 	{
-		int			childRTindex = lfirsti(l);
+		int			childRTindex = lfirst_int(l);
 		Oid			childOID = getrelid(childRTindex, parse->rtable);
 		Query	   *subquery;
 		Plan	   *subplan;
@@ -461,6 +525,42 @@ inheritance_planner(Query *parse, List *inheritlist)
 		/* Generate plan */
 		subplan = grouping_planner(subquery, 0.0 /* retrieve all tuples */ );
 		subplans = lappend(subplans, subplan);
+
+		/*
+		 * XXX my goodness this next bit is ugly.  Really need to think about
+		 * ways to rein in planner's habit of scribbling on its input.
+		 *
+		 * Planning of the subquery might have modified the rangetable,
+		 * either by addition of RTEs due to expansion of inherited source
+		 * tables, or by changes of the Query structures inside subquery
+		 * RTEs.  We have to ensure that this gets propagated back to the
+		 * master copy.  However, if we aren't done planning yet, we also
+		 * need to ensure that subsequent calls to grouping_planner have
+		 * virgin sub-Queries to work from.  So, if we are at the last
+		 * list entry, just copy the subquery rangetable back to the master
+		 * copy; if we are not, then extend the master copy by adding
+		 * whatever the subquery added.  (We assume these added entries
+		 * will go untouched by the future grouping_planner calls.  We are
+		 * also effectively assuming that sub-Queries will get planned
+		 * identically each time, or at least that the impacts on their
+		 * rangetables will be the same each time.  Did I say this is ugly?)
+		 */
+		if (lnext(l) == NULL)
+			parse->rtable = subquery->rtable;
+		else
+		{
+			int		subrtlength = list_length(subquery->rtable);
+
+			if (subrtlength > mainrtlength)
+			{
+				List	   *subrt;
+
+				subrt = list_copy_tail(subquery->rtable, mainrtlength);
+				parse->rtable = list_concat(parse->rtable, subrt);
+				mainrtlength = subrtlength;
+			}
+		}
+
 		/* Save preprocessed tlist from first rel for use in Append */
 		if (tlist == NIL)
 			tlist = subplan->targetlist;
@@ -485,14 +585,11 @@ inheritance_planner(Query *parse, List *inheritlist)
  * tuple_fraction is the fraction of tuples we expect will be retrieved
  *
  * tuple_fraction is interpreted as follows:
- *	  < 0: determine fraction by inspection of query (normal case)
- *	  0: expect all tuples to be retrieved
+ *	  0: expect all tuples to be retrieved (normal case)
  *	  0 < tuple_fraction < 1: expect the given fraction of tuples available
  *		from the plan to be retrieved
  *	  tuple_fraction >= 1: tuple_fraction is the absolute number of tuples
  *		expected to be retrieved (ie, a LIMIT specification)
- * The normal case is to pass -1, but some callers pass values >= 0 to
- * override this routine's determination of the appropriate fraction.
  *
  * Returns a query plan.  Also, parse->query_pathkeys is returned as the
  * actual output ordering of the plan (in pathkey format).
@@ -508,11 +605,23 @@ grouping_planner(Query *parse, double tuple_fraction)
 
 	if (parse->setOperations)
 	{
+		List	   *set_sortclauses;
+
 		/*
 		 * Construct the plan for set operations.  The result will not
 		 * need any work except perhaps a top-level sort and/or LIMIT.
 		 */
-		result_plan = plan_set_operations(parse);
+		result_plan = plan_set_operations(parse,
+										  &set_sortclauses);
+
+		/*
+		 * Calculate pathkeys representing the sort order (if any) of the
+		 * set operation's result.  We have to do this before overwriting
+		 * the sort key information...
+		 */
+		current_pathkeys = make_pathkeys_for_sortclauses(set_sortclauses,
+												result_plan->targetlist);
+		current_pathkeys = canonicalize_pathkeys(parse, current_pathkeys);
 
 		/*
 		 * We should not need to call preprocess_targetlist, since we must
@@ -530,19 +639,12 @@ grouping_planner(Query *parse, double tuple_fraction)
 		 * already, but let's make sure).
 		 */
 		if (parse->rowMarks)
-			elog(ERROR, "SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT");
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT")));
 
 		/*
-		 * We set current_pathkeys NIL indicating we do not know sort
-		 * order.  This is correct when the top set operation is UNION
-		 * ALL, since the appended-together results are unsorted even if
-		 * the subplans were sorted.  For other set operations we could be
-		 * smarter --- room for future improvement!
-		 */
-		current_pathkeys = NIL;
-
-		/*
-		 * Calculate pathkeys that represent ordering requirements
+		 * Calculate pathkeys that represent result ordering requirements
 		 */
 		sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
 													  tlist);
@@ -559,76 +661,24 @@ grouping_planner(Query *parse, double tuple_fraction)
 		double		sub_tuple_fraction;
 		Path	   *cheapest_path;
 		Path	   *sorted_path;
+		Path	   *best_path;
 		double		dNumGroups = 0;
 		long		numGroups = 0;
-		int			numAggs = 0;
-		int			numGroupCols = length(parse->groupClause);
+		AggClauseCounts agg_counts;
+		int			numGroupCols = list_length(parse->groupClause);
 		bool		use_hashed_grouping = false;
 
-		/* Preprocess targetlist in case we are inside an INSERT/UPDATE. */
-		tlist = preprocess_targetlist(tlist,
-									  parse->commandType,
-									  parse->resultRelation,
-									  parse->rtable);
-
-		/*
-		 * Add TID targets for rels selected FOR UPDATE (should this be
-		 * done in preprocess_targetlist?).  The executor uses the TID to
-		 * know which rows to lock, much as for UPDATE or DELETE.
-		 */
-		if (parse->rowMarks)
-		{
-			List	   *l;
-
-			/*
-			 * We've got trouble if the FOR UPDATE appears inside
-			 * grouping, since grouping renders a reference to individual
-			 * tuple CTIDs invalid.  This is also checked at parse time,
-			 * but that's insufficient because of rule substitution, query
-			 * pullup, etc.
-			 */
-			CheckSelectForUpdate(parse);
-
-			/*
-			 * Currently the executor only supports FOR UPDATE at top
-			 * level
-			 */
-			if (PlannerQueryLevel > 1)
-				elog(ERROR, "SELECT FOR UPDATE is not allowed in subselects");
+		MemSet(&agg_counts, 0, sizeof(AggClauseCounts));
 
-			foreach(l, parse->rowMarks)
-			{
-				Index		rti = lfirsti(l);
-				char	   *resname;
-				Resdom	   *resdom;
-				Var		   *var;
-				TargetEntry *ctid;
-
-				resname = (char *) palloc(32);
-				snprintf(resname, 32, "ctid%u", rti);
-				resdom = makeResdom(length(tlist) + 1,
-									TIDOID,
-									-1,
-									resname,
-									true);
-
-				var = makeVar(rti,
-							  SelfItemPointerAttributeNumber,
-							  TIDOID,
-							  -1,
-							  0);
-
-				ctid = makeTargetEntry(resdom, (Expr *) var);
-				tlist = lappend(tlist, ctid);
-			}
-		}
+		/* Preprocess targetlist */
+		tlist = preprocess_targetlist(parse, tlist);
 
 		/*
 		 * Generate appropriate target list for subplan; may be different
 		 * from tlist if grouping or aggregation is needed.
 		 */
 		sub_tlist = make_subplanTargetList(parse, tlist,
-										   &groupColIdx, &need_tlist_eval);
+										 &groupColIdx, &need_tlist_eval);
 
 		/*
 		 * Calculate pathkeys that represent grouping/ordering
@@ -641,18 +691,19 @@ grouping_planner(Query *parse, double tuple_fraction)
 
 		/*
 		 * Will need actual number of aggregates for estimating costs.
-		 * Also, it's possible that optimization has eliminated all
-		 * aggregates, and we may as well check for that here.
 		 *
-		 * Note: we do not attempt to detect duplicate aggregates here;
-		 * a somewhat-overestimated count is okay for our present purposes.
+		 * Note: we do not attempt to detect duplicate aggregates here; a
+		 * somewhat-overestimated count is okay for our present purposes.
+		 *
+		 * Note: think not that we can turn off hasAggs if we find no aggs.
+		 * It is possible for constant-expression simplification to remove
+		 * all explicit references to aggs, but we still have to follow
+		 * the aggregate semantics (eg, producing only one output row).
 		 */
 		if (parse->hasAggs)
 		{
-			numAggs = count_agg_clause((Node *) tlist) +
-				count_agg_clause(parse->havingQual);
-			if (numAggs == 0)
-				parse->hasAggs = false;
+			count_agg_clauses((Node *) tlist, &agg_counts);
+			count_agg_clauses(parse->havingQual, &agg_counts);
 		}
 
 		/*
@@ -673,29 +724,6 @@ grouping_planner(Query *parse, double tuple_fraction)
 		else
 			parse->query_pathkeys = NIL;
 
-		/*
-		 * Figure out whether we expect to retrieve all the tuples that
-		 * the plan can generate, or to stop early due to outside factors
-		 * such as a cursor.  If the caller passed a value >= 0, believe
-		 * that value, else do our own examination of the query context.
-		 */
-		if (tuple_fraction < 0.0)
-		{
-			/* Initial assumption is we need all the tuples */
-			tuple_fraction = 0.0;
-
-			/*
-			 * Check for retrieve-into-portal, ie DECLARE CURSOR.
-			 *
-			 * We have no real idea how many tuples the user will ultimately
-			 * FETCH from a cursor, but it seems a good bet that he
-			 * doesn't want 'em all.  Optimize for 10% retrieval (you
-			 * gotta better number?  Should this be a SETtable parameter?)
-			 */
-			if (parse->isPortal)
-				tuple_fraction = 0.10;
-		}
-
 		/*
 		 * Adjust tuple_fraction if we see that we are going to apply
 		 * limiting/grouping/aggregation/etc.  This is not overridable by
@@ -859,334 +887,255 @@ grouping_planner(Query *parse, double tuple_fraction)
 					  &cheapest_path, &sorted_path);
 
 		/*
-		 * We couldn't canonicalize group_pathkeys and sort_pathkeys before
-		 * running query_planner(), so do it now.
+		 * We couldn't canonicalize group_pathkeys and sort_pathkeys
+		 * before running query_planner(), so do it now.
 		 */
 		group_pathkeys = canonicalize_pathkeys(parse, group_pathkeys);
 		sort_pathkeys = canonicalize_pathkeys(parse, sort_pathkeys);
 
 		/*
-		 * Consider whether we might want to use hashed grouping.
+		 * If grouping, estimate the number of groups.  (We can't do this
+		 * until after running query_planner(), either.)  Then decide
+		 * whether we want to use hashed grouping.
 		 */
 		if (parse->groupClause)
 		{
-			List   *groupExprs;
+			List	   *groupExprs;
+			double		cheapest_path_rows;
 
 			/*
-			 * Always estimate the number of groups.  We can't do this until
-			 * after running query_planner(), either.
+			 * Beware of the possibility that cheapest_path->parent is NULL.
+			 * This could happen if user does something silly like
+			 *		SELECT 'foo' GROUP BY 1;
 			 */
+			if (cheapest_path->parent)
+				cheapest_path_rows = cheapest_path->parent->rows;
+			else
+				cheapest_path_rows = 1; /* assume non-set result */
+
 			groupExprs = get_sortgrouplist_exprs(parse->groupClause,
 												 parse->targetList);
 			dNumGroups = estimate_num_groups(parse,
 											 groupExprs,
-											 cheapest_path->parent->rows);
+											 cheapest_path_rows);
 			/* Also want it as a long int --- but 'ware overflow! */
 			numGroups = (long) Min(dNumGroups, (double) LONG_MAX);
 
-			/*
-			 * Check can't-do-it conditions, including whether the grouping
-			 * operators are hashjoinable.
-			 *
-			 * Executor doesn't support hashed aggregation with DISTINCT
-			 * aggregates.  (Doing so would imply storing *all* the input
-			 * values in the hash table, which seems like a certain loser.)
-			 */
-			if (!enable_hashagg || !hash_safe_grouping(parse))
-				use_hashed_grouping = false;
-			else if (parse->hasAggs &&
-					 (contain_distinct_agg_clause((Node *) tlist) ||
-					  contain_distinct_agg_clause(parse->havingQual)))
-				use_hashed_grouping = false;
-			else
-			{
-				/*
-				 * Use hashed grouping if (a) we think we can fit the
-				 * hashtable into SortMem, *and* (b) the estimated cost
-				 * is no more than doing it the other way.  While avoiding
-				 * the need for sorted input is usually a win, the fact
-				 * that the output won't be sorted may be a loss; so we
-				 * need to do an actual cost comparison.
-				 *
-				 * In most cases we have no good way to estimate the size of
-				 * the transition value needed by an aggregate; arbitrarily
-				 * assume it is 100 bytes.  Also set the overhead per hashtable
-				 * entry at 64 bytes.
-				 */
-				int		hashentrysize = cheapest_path->parent->width + 64 +
-					numAggs * 100;
-
-				if (hashentrysize * dNumGroups <= SortMem * 1024L)
-				{
-					/*
-					 * Okay, do the cost comparison.  We need to consider
-					 *	cheapest_path + hashagg [+ final sort]
-					 * versus either
-					 *	cheapest_path [+ sort] + group or agg [+ final sort]
-					 * or
-					 *	presorted_path + group or agg [+ final sort]
-					 * where brackets indicate a step that may not be needed.
-					 * We assume query_planner() will have returned a
-					 * presorted path only if it's a winner compared to
-					 * cheapest_path for this purpose.
-					 *
-					 * These path variables are dummies that just hold cost
-					 * fields; we don't make actual Paths for these steps.
-					 */
-					Path		hashed_p;
-					Path		sorted_p;
-
-					cost_agg(&hashed_p, parse,
-							 AGG_HASHED, numAggs,
-							 numGroupCols, dNumGroups,
-							 cheapest_path->startup_cost,
-							 cheapest_path->total_cost,
-							 cheapest_path->parent->rows);
-					/* Result of hashed agg is always unsorted */
-					if (sort_pathkeys)
-						cost_sort(&hashed_p, parse, sort_pathkeys,
-								  hashed_p.total_cost,
-								  dNumGroups,
-								  cheapest_path->parent->width);
-
-					if (sorted_path)
-					{
-						sorted_p.startup_cost = sorted_path->startup_cost;
-						sorted_p.total_cost = sorted_path->total_cost;
-						current_pathkeys = sorted_path->pathkeys;
-					}
-					else
-					{
-						sorted_p.startup_cost = cheapest_path->startup_cost;
-						sorted_p.total_cost = cheapest_path->total_cost;
-						current_pathkeys = cheapest_path->pathkeys;
-					}
-					if (!pathkeys_contained_in(group_pathkeys,
-											   current_pathkeys))
-					{
-						cost_sort(&sorted_p, parse, group_pathkeys,
-								  sorted_p.total_cost,
-								  cheapest_path->parent->rows,
-								  cheapest_path->parent->width);
-						current_pathkeys = group_pathkeys;
-					}
-					if (parse->hasAggs)
-						cost_agg(&sorted_p, parse,
-								 AGG_SORTED, numAggs,
-								 numGroupCols, dNumGroups,
-								 sorted_p.startup_cost,
-								 sorted_p.total_cost,
-								 cheapest_path->parent->rows);
-					else
-						cost_group(&sorted_p, parse,
-								   numGroupCols, dNumGroups,
-								   sorted_p.startup_cost,
-								   sorted_p.total_cost,
-								   cheapest_path->parent->rows);
-					/* The Agg or Group node will preserve ordering */
-					if (sort_pathkeys &&
-						!pathkeys_contained_in(sort_pathkeys,
-											   current_pathkeys))
-					{
-						cost_sort(&sorted_p, parse, sort_pathkeys,
-								  sorted_p.total_cost,
-								  dNumGroups,
-								  cheapest_path->parent->width);
-					}
-
-					/*
-					 * Now make the decision using the top-level tuple
-					 * fraction.  First we have to convert an absolute
-					 * count (LIMIT) into fractional form.
-					 */
-					if (tuple_fraction >= 1.0)
-						tuple_fraction /= dNumGroups;
-
-					if (compare_fractional_path_costs(&hashed_p, &sorted_p,
-													  tuple_fraction) <= 0)
-					{
-						/* Hashed is cheaper, so use it */
-						use_hashed_grouping = true;
-					}
-				}
-			}
+			use_hashed_grouping =
+				choose_hashed_grouping(parse, tuple_fraction,
+									   cheapest_path, sorted_path,
+									   sort_pathkeys, group_pathkeys,
+									   dNumGroups, &agg_counts);
 		}
 
 		/*
-		 * Select the best path and create a plan to execute it.
-		 *
-		 * If we are doing hashed grouping, we will always read all the
-		 * input tuples, so use the cheapest-total path.  Otherwise,
-		 * trust query_planner's decision about which to use.
+		 * Select the best path.  If we are doing hashed grouping, we will
+		 * always read all the input tuples, so use the cheapest-total
+		 * path. Otherwise, trust query_planner's decision about which to use.
 		 */
-		if (sorted_path && !use_hashed_grouping)
-		{
-			result_plan = create_plan(parse, sorted_path);
-			current_pathkeys = sorted_path->pathkeys;
-		}
+		if (use_hashed_grouping || !sorted_path)
+			best_path = cheapest_path;
 		else
-		{
-			result_plan = create_plan(parse, cheapest_path);
-			current_pathkeys = cheapest_path->pathkeys;
-		}
+			best_path = sorted_path;
 
 		/*
-		 * create_plan() returns a plan with just a "flat" tlist of required
-		 * Vars.  Usually we need to insert the sub_tlist as the tlist of the
-		 * top plan node.  However, we can skip that if we determined that
-		 * whatever query_planner chose to return will be good enough.
+		 * Check to see if it's possible to optimize MIN/MAX aggregates.
+		 * If so, we will forget all the work we did so far to choose a
+		 * "regular" path ... but we had to do it anyway to be able to
+		 * tell which way is cheaper.
 		 */
-		if (need_tlist_eval)
+		result_plan = optimize_minmax_aggregates(parse,
+												 tlist,
+												 best_path);
+		if (result_plan != NULL)
 		{
 			/*
-			 * If the top-level plan node is one that cannot do expression
-			 * evaluation, we must insert a Result node to project the desired
-			 * tlist.
-			 * Currently, the only plan node we might see here that falls into
-			 * that category is Append.
-			 */
-			if (IsA(result_plan, Append))
-			{
-				result_plan = (Plan *) make_result(sub_tlist, NULL,
-												   result_plan);
-			}
-			else
-			{
-				/*
-				 * Otherwise, just replace the subplan's flat tlist with
-				 * the desired tlist.
-				 */
-				result_plan->targetlist = sub_tlist;
-			}
-			/*
-			 * Also, account for the cost of evaluation of the sub_tlist.
-			 *
-			 * Up to now, we have only been dealing with "flat" tlists,
-			 * containing just Vars.  So their evaluation cost is zero
-			 * according to the model used by cost_qual_eval() (or if you
-			 * prefer, the cost is factored into cpu_tuple_cost).  Thus we can
-			 * avoid accounting for tlist cost throughout query_planner() and
-			 * subroutines.  But now we've inserted a tlist that might contain
-			 * actual operators, sub-selects, etc --- so we'd better account
-			 * for its cost.
-			 *
-			 * Below this point, any tlist eval cost for added-on nodes should
-			 * be accounted for as we create those nodes.  Presently, of the
-			 * node types we can add on, only Agg and Group project new tlists
-			 * (the rest just copy their input tuples) --- so make_agg() and
-			 * make_group() are responsible for computing the added cost.
+			 * optimize_minmax_aggregates generated the full plan, with
+			 * the right tlist, and it has no sort order.
 			 */
-			cost_qual_eval(&tlist_cost, sub_tlist);
-			result_plan->startup_cost += tlist_cost.startup;
-			result_plan->total_cost += tlist_cost.startup +
-				tlist_cost.per_tuple * result_plan->plan_rows;
+			current_pathkeys = NIL;
 		}
 		else
 		{
 			/*
-			 * Since we're using query_planner's tlist and not the one
-			 * make_subplanTargetList calculated, we have to refigure
-			 * any grouping-column indexes make_subplanTargetList computed.
+			 * Normal case --- create a plan according to query_planner's
+			 * results.
 			 */
-			locate_grouping_columns(parse, tlist, result_plan->targetlist,
-									groupColIdx);
-		}
+			result_plan = create_plan(parse, best_path);
+			current_pathkeys = best_path->pathkeys;
 
-		/*
-		 * Insert AGG or GROUP node if needed, plus an explicit sort step
-		 * if necessary.
-		 *
-		 * HAVING clause, if any, becomes qual of the Agg node
-		 */
-		if (use_hashed_grouping)
-		{
-			/* Hashed aggregate plan --- no sort needed */
-			result_plan = (Plan *) make_agg(parse,
-											tlist,
-											(List *) parse->havingQual,
-											AGG_HASHED,
-											numGroupCols,
-											groupColIdx,
-											numGroups,
-											numAggs,
-											result_plan);
-			/* Hashed aggregation produces randomly-ordered results */
-			current_pathkeys = NIL;
-		}
-		else if (parse->hasAggs)
-		{
-			/* Plain aggregate plan --- sort if needed */
-			AggStrategy aggstrategy;
-
-			if (parse->groupClause)
+			/*
+			 * create_plan() returns a plan with just a "flat" tlist of
+			 * required Vars.  Usually we need to insert the sub_tlist as the
+			 * tlist of the top plan node.	However, we can skip that if we
+			 * determined that whatever query_planner chose to return will be
+			 * good enough.
+			 */
+			if (need_tlist_eval)
 			{
-				if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
+				/*
+				 * If the top-level plan node is one that cannot do expression
+				 * evaluation, we must insert a Result node to project the
+				 * desired tlist.
+				 */
+				if (!is_projection_capable_plan(result_plan))
 				{
-					result_plan = make_groupsortplan(parse,
-													 parse->groupClause,
-													 groupColIdx,
-													 result_plan);
-					current_pathkeys = group_pathkeys;
+					result_plan = (Plan *) make_result(sub_tlist, NULL,
+													   result_plan);
+				}
+				else
+				{
+					/*
+					 * Otherwise, just replace the subplan's flat tlist with
+					 * the desired tlist.
+					 */
+					result_plan->targetlist = sub_tlist;
 				}
-				aggstrategy = AGG_SORTED;
+
 				/*
-				 * The AGG node will not change the sort ordering of its
-				 * groups, so current_pathkeys describes the result too.
+				 * Also, account for the cost of evaluation of the sub_tlist.
+				 *
+				 * Up to now, we have only been dealing with "flat" tlists,
+				 * containing just Vars.  So their evaluation cost is zero
+				 * according to the model used by cost_qual_eval() (or if you
+				 * prefer, the cost is factored into cpu_tuple_cost).  Thus we
+				 * can avoid accounting for tlist cost throughout
+				 * query_planner() and subroutines.  But now we've inserted a
+				 * tlist that might contain actual operators, sub-selects, etc
+				 * --- so we'd better account for its cost.
+				 *
+				 * Below this point, any tlist eval cost for added-on nodes
+				 * should be accounted for as we create those nodes.
+				 * Presently, of the node types we can add on, only Agg and
+				 * Group project new tlists (the rest just copy their input
+				 * tuples) --- so make_agg() and make_group() are responsible
+				 * for computing the added cost.
 				 */
+				cost_qual_eval(&tlist_cost, sub_tlist);
+				result_plan->startup_cost += tlist_cost.startup;
+				result_plan->total_cost += tlist_cost.startup +
+					tlist_cost.per_tuple * result_plan->plan_rows;
 			}
 			else
 			{
-				aggstrategy = AGG_PLAIN;
-				/* Result will be only one row anyway; no sort order */
-				current_pathkeys = NIL;
+				/*
+				 * Since we're using query_planner's tlist and not the one
+				 * make_subplanTargetList calculated, we have to refigure any
+				 * grouping-column indexes make_subplanTargetList computed.
+				 */
+				locate_grouping_columns(parse, tlist, result_plan->targetlist,
+										groupColIdx);
 			}
 
-			result_plan = (Plan *) make_agg(parse,
-											tlist,
-											(List *) parse->havingQual,
-											aggstrategy,
-											numGroupCols,
-											groupColIdx,
-											numGroups,
-											numAggs,
-											result_plan);
-		}
-		else
-		{
 			/*
-			 * If there are no Aggs, we shouldn't have any HAVING qual anymore
+			 * Insert AGG or GROUP node if needed, plus an explicit sort step
+			 * if necessary.
+			 *
+			 * HAVING clause, if any, becomes qual of the Agg or Group node.
 			 */
-			Assert(parse->havingQual == NULL);
+			if (use_hashed_grouping)
+			{
+				/* Hashed aggregate plan --- no sort needed */
+				result_plan = (Plan *) make_agg(parse,
+												tlist,
+												(List *) parse->havingQual,
+												AGG_HASHED,
+												numGroupCols,
+												groupColIdx,
+												numGroups,
+												agg_counts.numAggs,
+												result_plan);
+				/* Hashed aggregation produces randomly-ordered results */
+				current_pathkeys = NIL;
+			}
+			else if (parse->hasAggs)
+			{
+				/* Plain aggregate plan --- sort if needed */
+				AggStrategy aggstrategy;
 
-			/*
-			 * If we have a GROUP BY clause, insert a group node (plus the
-			 * appropriate sort node, if necessary).
-			 */
-			if (parse->groupClause)
+				if (parse->groupClause)
+				{
+					if (!pathkeys_contained_in(group_pathkeys,
+											   current_pathkeys))
+					{
+						result_plan = (Plan *)
+							make_sort_from_groupcols(parse,
+													 parse->groupClause,
+													 groupColIdx,
+													 result_plan);
+						current_pathkeys = group_pathkeys;
+					}
+					aggstrategy = AGG_SORTED;
+
+					/*
+					 * The AGG node will not change the sort ordering of its
+					 * groups, so current_pathkeys describes the result too.
+					 */
+				}
+				else
+				{
+					aggstrategy = AGG_PLAIN;
+					/* Result will be only one row anyway; no sort order */
+					current_pathkeys = NIL;
+				}
+
+				result_plan = (Plan *) make_agg(parse,
+												tlist,
+												(List *) parse->havingQual,
+												aggstrategy,
+												numGroupCols,
+												groupColIdx,
+												numGroups,
+												agg_counts.numAggs,
+												result_plan);
+			}
+			else if (parse->groupClause)
 			{
 				/*
-				 * Add an explicit sort if we couldn't make the path come out
-				 * the way the GROUP node needs it.
+				 * GROUP BY without aggregation, so insert a group node (plus
+				 * the appropriate sort node, if necessary).
+				 *
+				 * Add an explicit sort if we couldn't make the path come
+				 * out the way the GROUP node needs it.
 				 */
 				if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
 				{
-					result_plan = make_groupsortplan(parse,
-													 parse->groupClause,
-													 groupColIdx,
-													 result_plan);
+					result_plan = (Plan *)
+						make_sort_from_groupcols(parse,
+												 parse->groupClause,
+												 groupColIdx,
+												 result_plan);
 					current_pathkeys = group_pathkeys;
 				}
 
 				result_plan = (Plan *) make_group(parse,
 												  tlist,
+												  (List *) parse->havingQual,
 												  numGroupCols,
 												  groupColIdx,
 												  dNumGroups,
 												  result_plan);
 				/* The Group node won't change sort ordering */
 			}
-		}
-	} /* end of if (setOperations) */
+			else if (parse->hasHavingQual)
+			{
+				/*
+				 * No aggregates, and no GROUP BY, but we have a HAVING qual.
+				 * This is a degenerate case in which we are supposed to emit
+				 * either 0 or 1 row depending on whether HAVING succeeds.
+				 * Furthermore, there cannot be any variables in either HAVING
+				 * or the targetlist, so we actually do not need the FROM table
+				 * at all!  We can just throw away the plan-so-far and generate
+				 * a Result node.  This is a sufficiently unusual corner case
+				 * that it's not worth contorting the structure of this routine
+				 * to avoid having to generate the plan in the first place.
+				 */
+				result_plan = (Plan *) make_result(tlist,
+												   parse->havingQual,
+												   NULL);
+			}
+		}						/* end of non-minmax-aggregate case */
+	}							/* end of if (setOperations) */
 
 	/*
 	 * If we were not able to make the plan come out in the right order,
@@ -1196,10 +1145,10 @@ grouping_planner(Query *parse, double tuple_fraction)
 	{
 		if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
 		{
-			result_plan = (Plan *) make_sort_from_sortclauses(parse,
-															  tlist,
-															  result_plan,
-															  parse->sortClause);
+			result_plan = (Plan *)
+				make_sort_from_sortclauses(parse,
+										   parse->sortClause,
+										   result_plan);
 			current_pathkeys = sort_pathkeys;
 		}
 	}
@@ -1209,23 +1158,23 @@ grouping_planner(Query *parse, double tuple_fraction)
 	 */
 	if (parse->distinctClause)
 	{
-		result_plan = (Plan *) make_unique(tlist, result_plan,
-										   parse->distinctClause);
+		result_plan = (Plan *) make_unique(result_plan, parse->distinctClause);
+
 		/*
 		 * If there was grouping or aggregation, leave plan_rows as-is
 		 * (ie, assume the result was already mostly unique).  If not,
 		 * it's reasonable to assume the UNIQUE filter has effects
 		 * comparable to GROUP BY.
 		 */
-		if (!parse->groupClause && !parse->hasAggs)
+		if (!parse->groupClause && !parse->hasHavingQual && !parse->hasAggs)
 		{
-			List   *distinctExprs;
+			List	   *distinctExprs;
 
 			distinctExprs = get_sortgrouplist_exprs(parse->distinctClause,
 													parse->targetList);
 			result_plan->plan_rows = estimate_num_groups(parse,
 														 distinctExprs,
-														 result_plan->plan_rows);
+												 result_plan->plan_rows);
 		}
 	}
 
@@ -1234,7 +1183,7 @@ grouping_planner(Query *parse, double tuple_fraction)
 	 */
 	if (parse->limitOffset || parse->limitCount)
 	{
-		result_plan = (Plan *) make_limit(tlist, result_plan,
+		result_plan = (Plan *) make_limit(result_plan,
 										  parse->limitOffset,
 										  parse->limitCount);
 	}
@@ -1248,6 +1197,146 @@ grouping_planner(Query *parse, double tuple_fraction)
 	return result_plan;
 }
 
+/*
+ * choose_hashed_grouping - should we use hashed grouping?
+ */
+static bool
+choose_hashed_grouping(Query *parse, double tuple_fraction,
+					   Path *cheapest_path, Path *sorted_path,
+					   List *sort_pathkeys, List *group_pathkeys,
+					   double dNumGroups, AggClauseCounts *agg_counts)
+{
+	int			numGroupCols = list_length(parse->groupClause);
+	double		cheapest_path_rows;
+	int			cheapest_path_width;
+	Size		hashentrysize;
+	List	   *current_pathkeys;
+	Path		hashed_p;
+	Path		sorted_p;
+
+	/*
+	 * Check can't-do-it conditions, including whether the grouping operators
+	 * are hashjoinable.
+	 *
+	 * Executor doesn't support hashed aggregation with DISTINCT aggregates.
+	 * (Doing so would imply storing *all* the input values in the hash table,
+	 * which seems like a certain loser.)
+	 */
+	if (!enable_hashagg)
+		return false;
+	if (agg_counts->numDistinctAggs != 0)
+		return false;
+	if (!hash_safe_grouping(parse))
+		return false;
+
+	/*
+	 * Don't do it if it doesn't look like the hashtable will fit into
+	 * work_mem.
+	 *
+	 * Beware here of the possibility that cheapest_path->parent is NULL.
+	 * This could happen if user does something silly like
+	 *		SELECT 'foo' GROUP BY 1;
+	 */
+	if (cheapest_path->parent)
+	{
+		cheapest_path_rows = cheapest_path->parent->rows;
+		cheapest_path_width = cheapest_path->parent->width;
+	}
+	else
+	{
+		cheapest_path_rows = 1;				/* assume non-set result */
+		cheapest_path_width = 100;			/* arbitrary */
+	}
+
+	/* Estimate per-hash-entry space at tuple width... */
+	hashentrysize = cheapest_path_width;
+	/* plus space for pass-by-ref transition values... */
+	hashentrysize += agg_counts->transitionSpace;
+	/* plus the per-hash-entry overhead */
+	hashentrysize += hash_agg_entry_size(agg_counts->numAggs);
+
+	if (hashentrysize * dNumGroups > work_mem * 1024L)
+		return false;
+
+	/*
+	 * See if the estimated cost is no more than doing it the other way.
+	 * While avoiding the need for sorted input is usually a win, the fact
+	 * that the output won't be sorted may be a loss; so we need to do an
+	 * actual cost comparison.
+	 *
+	 * We need to consider
+	 *		cheapest_path + hashagg [+ final sort]
+	 * versus either
+	 *		cheapest_path [+ sort] + group or agg [+ final sort]
+	 * or
+	 *		presorted_path + group or agg [+ final sort]
+	 * where brackets indicate a step that may not be needed. We assume
+	 * query_planner() will have returned a presorted path only if it's a
+	 * winner compared to cheapest_path for this purpose.
+	 *
+	 * These path variables are dummies that just hold cost fields; we don't
+	 * make actual Paths for these steps.
+	 */
+	cost_agg(&hashed_p, parse, AGG_HASHED, agg_counts->numAggs,
+			 numGroupCols, dNumGroups,
+			 cheapest_path->startup_cost, cheapest_path->total_cost,
+			 cheapest_path_rows);
+	/* Result of hashed agg is always unsorted */
+	if (sort_pathkeys)
+		cost_sort(&hashed_p, parse, sort_pathkeys, hashed_p.total_cost,
+				  dNumGroups, cheapest_path_width);
+
+	if (sorted_path)
+	{
+		sorted_p.startup_cost = sorted_path->startup_cost;
+		sorted_p.total_cost = sorted_path->total_cost;
+		current_pathkeys = sorted_path->pathkeys;
+	}
+	else
+	{
+		sorted_p.startup_cost = cheapest_path->startup_cost;
+		sorted_p.total_cost = cheapest_path->total_cost;
+		current_pathkeys = cheapest_path->pathkeys;
+	}
+	if (!pathkeys_contained_in(group_pathkeys,
+							   current_pathkeys))
+	{
+		cost_sort(&sorted_p, parse, group_pathkeys, sorted_p.total_cost,
+				  cheapest_path_rows, cheapest_path_width);
+		current_pathkeys = group_pathkeys;
+	}
+
+	if (parse->hasAggs)
+		cost_agg(&sorted_p, parse, AGG_SORTED, agg_counts->numAggs,
+				 numGroupCols, dNumGroups,
+				 sorted_p.startup_cost, sorted_p.total_cost,
+				 cheapest_path_rows);
+	else
+		cost_group(&sorted_p, parse, numGroupCols, dNumGroups,
+				   sorted_p.startup_cost, sorted_p.total_cost,
+				   cheapest_path_rows);
+	/* The Agg or Group node will preserve ordering */
+	if (sort_pathkeys &&
+		!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
+		cost_sort(&sorted_p, parse, sort_pathkeys, sorted_p.total_cost,
+				  dNumGroups, cheapest_path_width);
+
+	/*
+	 * Now make the decision using the top-level tuple fraction.  First we
+	 * have to convert an absolute count (LIMIT) into fractional form.
+	 */
+	if (tuple_fraction >= 1.0)
+		tuple_fraction /= dNumGroups;
+
+	if (compare_fractional_path_costs(&hashed_p, &sorted_p,
+									  tuple_fraction) < 0)
+	{
+		/* Hashed is cheaper, so use it */
+		return true;
+	}
+	return false;
+}
+
 /*
  * hash_safe_grouping - are grouping operators hashable?
  *
@@ -1257,7 +1346,7 @@ grouping_planner(Query *parse, double tuple_fraction)
 static bool
 hash_safe_grouping(Query *parse)
 {
-	List	   *gl;
+	ListCell   *gl;
 
 	foreach(gl, parse->groupClause)
 	{
@@ -1266,7 +1355,9 @@ hash_safe_grouping(Query *parse)
 		Operator	optup;
 		bool		oprcanhash;
 
-		optup = equality_oper(tle->resdom->restype, false);
+		optup = equality_oper(exprType((Node *) tle->expr), true);
+		if (!optup)
+			return false;
 		oprcanhash = ((Form_pg_operator) GETSTRUCT(optup))->oprcanhash;
 		ReleaseSysCache(optup);
 		if (!oprcanhash)
@@ -1279,19 +1370,18 @@ hash_safe_grouping(Query *parse)
  * make_subplanTargetList
  *	  Generate appropriate target list when grouping is required.
  *
- * When grouping_planner inserts Aggregate or Group plan nodes above
- * the result of query_planner, we typically want to pass a different
+ * When grouping_planner inserts Aggregate, Group, or Result plan nodes
+ * above the result of query_planner, we typically want to pass a different
  * target list to query_planner than the outer plan nodes should have.
  * This routine generates the correct target list for the subplan.
  *
  * The initial target list passed from the parser already contains entries
  * for all ORDER BY and GROUP BY expressions, but it will not have entries
  * for variables used only in HAVING clauses; so we need to add those
- * variables to the subplan target list.  Also, if we are doing either
- * grouping or aggregation, we flatten all expressions except GROUP BY items
- * into their component variables; the other expressions will be computed by
- * the inserted nodes rather than by the subplan.  For example,
- * given a query like
+ * variables to the subplan target list.  Also, we flatten all expressions
+ * except GROUP BY items into their component variables; the other expressions
+ * will be computed by the inserted nodes rather than by the subplan.
+ * For example, given a query like
  *		SELECT a+b,SUM(c+d) FROM table GROUP BY a+b;
  * we want to pass this targetlist to the subplan:
  *		a,b,c,d,a+b
@@ -1331,10 +1421,10 @@ make_subplanTargetList(Query *parse,
 	*groupColIdx = NULL;
 
 	/*
-	 * If we're not grouping or aggregating, nothing to do here;
+	 * If we're not grouping or aggregating, there's nothing to do here;
 	 * query_planner should receive the unmodified target list.
 	 */
-	if (!parse->hasAggs && !parse->groupClause && !parse->havingQual)
+	if (!parse->hasAggs && !parse->groupClause && !parse->hasHavingQual)
 	{
 		*need_tlist_eval = true;
 		return tlist;
@@ -1348,7 +1438,7 @@ make_subplanTargetList(Query *parse,
 	sub_tlist = flatten_tlist(tlist);
 	extravars = pull_var_clause(parse->havingQual, false);
 	sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
-	freeList(extravars);
+	list_free(extravars);
 	*need_tlist_eval = false;	/* only eval if not flat tlist */
 
 	/*
@@ -1357,12 +1447,12 @@ make_subplanTargetList(Query *parse,
 	 * already), and make an array showing where the group columns are in
 	 * the sub_tlist.
 	 */
-	numCols = length(parse->groupClause);
+	numCols = list_length(parse->groupClause);
 	if (numCols > 0)
 	{
 		int			keyno = 0;
 		AttrNumber *grpColIdx;
-		List	   *gl;
+		ListCell   *gl;
 
 		grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		*groupColIdx = grpColIdx;
@@ -1372,7 +1462,7 @@ make_subplanTargetList(Query *parse,
 			GroupClause *grpcl = (GroupClause *) lfirst(gl);
 			Node	   *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
 			TargetEntry *te = NULL;
-			List	   *sl;
+			ListCell   *sl;
 
 			/* Find or make a matching sub_tlist entry */
 			foreach(sl, sub_tlist)
@@ -1383,18 +1473,16 @@ make_subplanTargetList(Query *parse,
 			}
 			if (!sl)
 			{
-				te = makeTargetEntry(makeResdom(length(sub_tlist) + 1,
-												exprType(groupexpr),
-												exprTypmod(groupexpr),
-												NULL,
-												false),
-									 (Expr *) groupexpr);
+				te = makeTargetEntry((Expr *) groupexpr,
+									 list_length(sub_tlist) + 1,
+									 NULL,
+									 false);
 				sub_tlist = lappend(sub_tlist, te);
-				*need_tlist_eval = true; /* it's not flat anymore */
+				*need_tlist_eval = true;		/* it's not flat anymore */
 			}
 
 			/* and save its resno */
-			grpColIdx[keyno++] = te->resdom->resno;
+			grpColIdx[keyno++] = te->resno;
 		}
 	}
 
@@ -1406,7 +1494,7 @@ make_subplanTargetList(Query *parse,
  *		Locate grouping columns in the tlist chosen by query_planner.
  *
  * This is only needed if we don't use the sub_tlist chosen by
- * make_subplanTargetList.  We have to forget the column indexes found
+ * make_subplanTargetList.	We have to forget the column indexes found
  * by that routine and re-locate the grouping vars in the real sub_tlist.
  */
 static void
@@ -1416,7 +1504,7 @@ locate_grouping_columns(Query *parse,
 						AttrNumber *groupColIdx)
 {
 	int			keyno = 0;
-	List	   *gl;
+	ListCell   *gl;
 
 	/*
 	 * No work unless grouping.
@@ -1433,7 +1521,7 @@ locate_grouping_columns(Query *parse,
 		GroupClause *grpcl = (GroupClause *) lfirst(gl);
 		Node	   *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
 		TargetEntry *te = NULL;
-		List	   *sl;
+		ListCell   *sl;
 
 		foreach(sl, sub_tlist)
 		{
@@ -1442,55 +1530,10 @@ locate_grouping_columns(Query *parse,
 				break;
 		}
 		if (!sl)
-			elog(ERROR, "locate_grouping_columns: failed");
-
-		groupColIdx[keyno++] = te->resdom->resno;
-	}
-}
+			elog(ERROR, "failed to locate grouping columns");
 
-/*
- * make_groupsortplan
- *		Add a Sort node to explicitly sort according to the GROUP BY clause.
- *
- * Note: the Sort node always just takes a copy of the subplan's tlist
- * plus ordering information.  (This might seem inefficient if the
- * subplan contains complex GROUP BY expressions, but in fact Sort
- * does not evaluate its targetlist --- it only outputs the same
- * tuples in a new order.  So the expressions we might be copying
- * are just dummies with no extra execution cost.)
- */
-static Plan *
-make_groupsortplan(Query *parse,
-				   List *groupClause,
-				   AttrNumber *grpColIdx,
-				   Plan *subplan)
-{
-	List	   *sort_tlist = new_unsorted_tlist(subplan->targetlist);
-	int			keyno = 0;
-	List	   *gl;
-
-	foreach(gl, groupClause)
-	{
-		GroupClause *grpcl = (GroupClause *) lfirst(gl);
-		TargetEntry *te = nth(grpColIdx[keyno] - 1, sort_tlist);
-		Resdom	   *resdom = te->resdom;
-
-		/*
-		 * Check for the possibility of duplicate group-by clauses ---
-		 * the parser should have removed 'em, but the Sort executor
-		 * will get terribly confused if any get through!
-		 */
-		if (resdom->reskey == 0)
-		{
-			/* OK, insert the ordering info needed by the executor. */
-			resdom->reskey = ++keyno;
-			resdom->reskeyop = grpcl->sortop;
-		}
+		groupColIdx[keyno++] = te->resno;
 	}
-
-	Assert(keyno > 0);
-
-	return (Plan *) make_sort(parse, sort_tlist, subplan, keyno);
 }
 
 /*
@@ -1500,13 +1543,14 @@ make_groupsortplan(Query *parse,
  * We need to transpose sort key info from the orig_tlist into new_tlist.
  * NOTE: this would not be good enough if we supported resjunk sort keys
  * for results of set operations --- then, we'd need to project a whole
- * new tlist to evaluate the resjunk columns.  For now, just elog if we
+ * new tlist to evaluate the resjunk columns.  For now, just ereport if we
  * find any resjunk columns in orig_tlist.
  */
 static List *
 postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
 {
-	List	   *l;
+	ListCell   *l;
+	ListCell   *orig_tlist_item = list_head(orig_tlist);
 
 	foreach(l, new_tlist)
 	{
@@ -1514,19 +1558,18 @@ postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
 		TargetEntry *orig_tle;
 
 		/* ignore resjunk columns in setop result */
-		if (new_tle->resdom->resjunk)
+		if (new_tle->resjunk)
 			continue;
 
-		Assert(orig_tlist != NIL);
-		orig_tle = (TargetEntry *) lfirst(orig_tlist);
-		orig_tlist = lnext(orig_tlist);
-		if (orig_tle->resdom->resjunk)
-			elog(ERROR, "postprocess_setop_tlist: resjunk output columns not implemented");
-		Assert(new_tle->resdom->resno == orig_tle->resdom->resno);
-		Assert(new_tle->resdom->restype == orig_tle->resdom->restype);
-		new_tle->resdom->ressortgroupref = orig_tle->resdom->ressortgroupref;
+		Assert(orig_tlist_item != NULL);
+		orig_tle = (TargetEntry *) lfirst(orig_tlist_item);
+		orig_tlist_item = lnext(orig_tlist_item);
+		if (orig_tle->resjunk)			/* should not happen */
+			elog(ERROR, "resjunk output columns are not implemented");
+		Assert(new_tle->resno == orig_tle->resno);
+		new_tle->ressortgroupref = orig_tle->ressortgroupref;
 	}
-	if (orig_tlist != NIL)
-		elog(ERROR, "postprocess_setop_tlist: resjunk output columns not implemented");
+	if (orig_tlist_item != NULL)
+		elog(ERROR, "resjunk output columns are not implemented");
 	return new_tlist;
 }