text: /*-------------------------------------------------------------------------
   *
   * parse_agg.c
   *	  handle aggregates and window functions in parser
   *
   * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/parser/parse_agg.c
   *
   *-------------------------------------------------------------------------
   */
  #include "postgres.h"
  
  #include "catalog/pg_aggregate.h"
  #include "catalog/pg_constraint.h"
  #include "catalog/pg_type.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
  #include "optimizer/optimizer.h"
  #include "parser/parse_agg.h"
  #include "parser/parse_clause.h"
  #include "parser/parse_coerce.h"
  #include "parser/parse_expr.h"
  #include "parser/parsetree.h"
  #include "rewrite/rewriteManip.h"
  #include "utils/builtins.h"
  #include "utils/lsyscache.h"
  
  
  typedef struct
  {
  	ParseState *pstate;
  	int			min_varlevel;
  	int			min_agglevel;
  	int			sublevels_up;
  } check_agg_arguments_context;
  
  typedef struct
  {
  	ParseState *pstate;
  	Query	   *qry;
  	bool		hasJoinRTEs;
  	List	   *groupClauses;
  	List	   *groupClauseCommonVars;
  	bool		have_non_var_grouping;
  	List	  **func_grouped_rels;
  	int			sublevels_up;
  	bool		in_agg_direct_args;
  } check_ungrouped_columns_context;
  
  static int	check_agg_arguments(ParseState *pstate,
  								List *directargs,
  								List *args,
  								Expr *filter);
  static bool check_agg_arguments_walker(Node *node,
  									   check_agg_arguments_context *context);
  static void check_ungrouped_columns(Node *node, ParseState *pstate, Query *qry,
  									List *groupClauses, List *groupClauseCommonVars,
  									bool have_non_var_grouping,
  									List **func_grouped_rels);
  static bool check_ungrouped_columns_walker(Node *node,
  										   check_ungrouped_columns_context *context);
  static void finalize_grouping_exprs(Node *node, ParseState *pstate, Query *qry,
  									List *groupClauses, bool hasJoinRTEs,
  									bool have_non_var_grouping);
  static bool finalize_grouping_exprs_walker(Node *node,
  										   check_ungrouped_columns_context *context);
  static void check_agglevels_and_constraints(ParseState *pstate, Node *expr);
  static List *expand_groupingset_node(GroupingSet *gs);
  static Node *make_agg_arg(Oid argtype, Oid argcollation);
  
  
  /*
   * transformAggregateCall -
   *		Finish initial transformation of an aggregate call
   *
   * parse_func.c has recognized the function as an aggregate, and has set up
   * all the fields of the Aggref except aggargtypes, aggdirectargs, args,
   * aggorder, aggdistinct and agglevelsup.  The passed-in args list has been
   * through standard expression transformation and type coercion to match the
   * agg's declared arg types, while the passed-in aggorder list hasn't been
   * transformed at all.
   *
   * Here we separate the args list into direct and aggregated args, storing the
   * former in agg->aggdirectargs and the latter in agg->args.  The regular
   * args, but not the direct args, are converted into a targetlist by inserting
   * TargetEntry nodes.  We then transform the aggorder and agg_distinct
   * specifications to produce lists of SortGroupClause nodes for agg->aggorder
   * and agg->aggdistinct.  (For a regular aggregate, this might result in
   * adding resjunk expressions to the targetlist; but for ordered-set
   * aggregates the aggorder list will always be one-to-one with the aggregated
   * args.)
   *
   * We must also determine which query level the aggregate actually belongs to,
   * set agglevelsup accordingly, and mark p_hasAggs true in the corresponding
   * pstate level.
   */
  void
  transformAggregateCall(ParseState *pstate, Aggref *agg,
  					   List *args, List *aggorder, bool agg_distinct)
  {
  	List	   *argtypes = NIL;
  	List	   *tlist = NIL;
  	List	   *torder = NIL;
  	List	   *tdistinct = NIL;
  	AttrNumber	attno = 1;
  	int			save_next_resno;
  	ListCell   *lc;
  
  	/*
  	 * Before separating the args into direct and aggregated args, make a list
  	 * of their data type OIDs for use later.
  	 */
  	foreach(lc, args)
  	{
  		Expr	   *arg = (Expr *) lfirst(lc);
  
  		argtypes = lappend_oid(argtypes, exprType((Node *) arg));
  	}
  	agg->aggargtypes = argtypes;
  
  	if (AGGKIND_IS_ORDERED_SET(agg->aggkind))
  	{
  		/*
  		 * For an ordered-set agg, the args list includes direct args and
  		 * aggregated args; we must split them apart.
  		 */
  		int			numDirectArgs = list_length(args) - list_length(aggorder);
  		List	   *aargs;
  		ListCell   *lc2;
  
  		Assert(numDirectArgs >= 0);
  
  		aargs = list_copy_tail(args, numDirectArgs);
  		agg->aggdirectargs = list_truncate(args, numDirectArgs);
  
  		/*
  		 * Build a tlist from the aggregated args, and make a sortlist entry
  		 * for each one.  Note that the expressions in the SortBy nodes are
  		 * ignored (they are the raw versions of the transformed args); we are
  		 * just looking at the sort information in the SortBy nodes.
  		 */
  		forboth(lc, aargs, lc2, aggorder)
  		{
  			Expr	   *arg = (Expr *) lfirst(lc);
  			SortBy	   *sortby = (SortBy *) lfirst(lc2);
  			TargetEntry *tle;
  
  			/* We don't bother to assign column names to the entries */
  			tle = makeTargetEntry(arg, attno++, NULL, false);
  			tlist = lappend(tlist, tle);
  
  			torder = addTargetToSortList(pstate, tle,
  										 torder, tlist, sortby);
  		}
  
  		/* Never any DISTINCT in an ordered-set agg */
  		Assert(!agg_distinct);
  	}
  	else
  	{
  		/* Regular aggregate, so it has no direct args */
  		agg->aggdirectargs = NIL;
  
  		/*
  		 * Transform the plain list of Exprs into a targetlist.
  		 */
  		foreach(lc, args)
  		{
  			Expr	   *arg = (Expr *) lfirst(lc);
  			TargetEntry *tle;
  
  			/* We don't bother to assign column names to the entries */
  			tle = makeTargetEntry(arg, attno++, NULL, false);
  			tlist = lappend(tlist, tle);
  		}
  
  		/*
  		 * If we have an ORDER BY, transform it.  This will add columns to the
  		 * tlist if they appear in ORDER BY but weren't already in the arg
  		 * list.  They will be marked resjunk = true so we can tell them apart
  		 * from regular aggregate arguments later.
  		 *
  		 * We need to mess with p_next_resno since it will be used to number
  		 * any new targetlist entries.
  		 */
  		save_next_resno = pstate->p_next_resno;
  		pstate->p_next_resno = attno;
  
  		torder = transformSortClause(pstate,
  									 aggorder,
  									 &tlist,
  									 EXPR_KIND_ORDER_BY,
  									 true /* force SQL99 rules */ );
  
  		/*
  		 * If we have DISTINCT, transform that to produce a distinctList.
  		 */
  		if (agg_distinct)
  		{
  			tdistinct = transformDistinctClause(pstate, &tlist, torder, true);
  
  			/*
  			 * Remove this check if executor support for hashed distinct for
  			 * aggregates is ever added.
  			 */
  			foreach(lc, tdistinct)
  			{
  				SortGroupClause *sortcl = (SortGroupClause *) lfirst(lc);
  
  				if (!OidIsValid(sortcl->sortop))
  				{
  					Node	   *expr = get_sortgroupclause_expr(sortcl, tlist);
  
  					ereport(ERROR,
  							(errcode(ERRCODE_UNDEFINED_FUNCTION),
  							 errmsg("could not identify an ordering operator for type %s",
  									format_type_be(exprType(expr))),
  							 errdetail("Aggregates with DISTINCT must be able to sort their inputs."),
  							 parser_errposition(pstate, exprLocation(expr))));
  				}
  			}
  		}
  
  		pstate->p_next_resno = save_next_resno;
  	}
  
  	/* Update the Aggref with the transformation results */
  	agg->args = tlist;
  	agg->aggorder = torder;
  	agg->aggdistinct = tdistinct;
  
  	check_agglevels_and_constraints(pstate, (Node *) agg);
  }
  
  /*
   * transformGroupingFunc
   *		Transform a GROUPING expression
   *
   * GROUPING() behaves very like an aggregate.  Processing of levels and nesting
   * is done as for aggregates.  We set p_hasAggs for these expressions too.
   */
  Node *
  transformGroupingFunc(ParseState *pstate, GroupingFunc *p)
  {
  	ListCell   *lc;
  	List	   *args = p->args;
  	List	   *result_list = NIL;
  	GroupingFunc *result = makeNode(GroupingFunc);
  
  	if (list_length(args) > 31)
  		ereport(ERROR,
  				(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
  				 errmsg("GROUPING must have fewer than 32 arguments"),
  				 parser_errposition(pstate, p->location)));
  
  	foreach(lc, args)
  	{
  		Node	   *current_result;
  
  		current_result = transformExpr(pstate, (Node *) lfirst(lc), pstate->p_expr_kind);
  
  		/* acceptability of expressions is checked later */
  
  		result_list = lappend(result_list, current_result);
  	}
  
  	result->args = result_list;
  	result->location = p->location;
  
  	check_agglevels_and_constraints(pstate, (Node *) result);
  
  	return (Node *) result;
  }
  
  /*
   * Aggregate functions and grouping operations (which are combined in the spec
   * as <set function specification>) are very similar with regard to level and
   * nesting restrictions (though we allow a lot more things than the spec does).
   * Centralise those restrictions here.
   */
  static void
  check_agglevels_and_constraints(ParseState *pstate, Node *expr)
  {
  	List	   *directargs = NIL;
  	List	   *args = NIL;
  	Expr	   *filter = NULL;
  	int			min_varlevel;
  	int			location = -1;
  	Index	   *p_levelsup;
  	const char *err;
  	bool		errkind;
  	bool		isAgg = IsA(expr, Aggref);
  
  	if (isAgg)
  	{
  		Aggref	   *agg = (Aggref *) expr;
  
  		directargs = agg->aggdirectargs;
  		args = agg->args;
  		filter = agg->aggfilter;
  		location = agg->location;
  		p_levelsup = &agg->agglevelsup;
  	}
  	else
  	{
  		GroupingFunc *grp = (GroupingFunc *) expr;
  
  		args = grp->args;
  		location = grp->location;
  		p_levelsup = &grp->agglevelsup;
  	}
  
  	/*
  	 * Check the arguments to compute the aggregate's level and detect
  	 * improper nesting.
  	 */
  	min_varlevel = check_agg_arguments(pstate,
  									   directargs,
  									   args,
  									   filter);
  
  	*p_levelsup = min_varlevel;
  
  	/* Mark the correct pstate level as having aggregates */
  	while (min_varlevel-- > 0)
  		pstate = pstate->parentParseState;
  	pstate->p_hasAggs = true;
  
  	/*
  	 * Check to see if the aggregate function is in an invalid place within
  	 * its aggregation query.
  	 *
  	 * For brevity we support two schemes for reporting an error here: set
  	 * "err" to a custom message, or set "errkind" true if the error context
  	 * is sufficiently identified by what ParseExprKindName will return, *and*
  	 * what it will return is just a SQL keyword.  (Otherwise, use a custom
  	 * message to avoid creating translation problems.)
  	 */
  	err = NULL;
  	errkind = false;
  	switch (pstate->p_expr_kind)
  	{
  		case EXPR_KIND_NONE:
  			Assert(false);		/* can't happen */
  			break;
  		case EXPR_KIND_OTHER:
  
  			/*
  			 * Accept aggregate/grouping here; caller must throw error if
  			 * wanted
  			 */
  			break;
  		case EXPR_KIND_JOIN_ON:
  		case EXPR_KIND_JOIN_USING:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in JOIN conditions");
  			else
  				err = _("grouping operations are not allowed in JOIN conditions");
  
  			break;
  		case EXPR_KIND_FROM_SUBSELECT:
  			/* Should only be possible in a LATERAL subquery */
  			Assert(pstate->p_lateral_active);
  
  			/*
  			 * Aggregate/grouping scope rules make it worth being explicit
  			 * here
  			 */
  			if (isAgg)
  				err = _("aggregate functions are not allowed in FROM clause of their own query level");
  			else
  				err = _("grouping operations are not allowed in FROM clause of their own query level");
  
  			break;
  		case EXPR_KIND_FROM_FUNCTION:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in functions in FROM");
  			else
  				err = _("grouping operations are not allowed in functions in FROM");
  
  			break;
  		case EXPR_KIND_WHERE:
  			errkind = true;
  			break;
  		case EXPR_KIND_POLICY:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in policy expressions");
  			else
  				err = _("grouping operations are not allowed in policy expressions");
  
  			break;
  		case EXPR_KIND_HAVING:
  			/* okay */
  			break;
  		case EXPR_KIND_FILTER:
  			errkind = true;
  			break;
  		case EXPR_KIND_WINDOW_PARTITION:
  			/* okay */
  			break;
  		case EXPR_KIND_WINDOW_ORDER:
  			/* okay */
  			break;
  		case EXPR_KIND_WINDOW_FRAME_RANGE:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in window RANGE");
  			else
  				err = _("grouping operations are not allowed in window RANGE");
  
  			break;
  		case EXPR_KIND_WINDOW_FRAME_ROWS:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in window ROWS");
  			else
  				err = _("grouping operations are not allowed in window ROWS");
  
  			break;
  		case EXPR_KIND_WINDOW_FRAME_GROUPS:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in window GROUPS");
  			else
  				err = _("grouping operations are not allowed in window GROUPS");
  
  			break;
  		case EXPR_KIND_SELECT_TARGET:
  			/* okay */
  			break;
  		case EXPR_KIND_INSERT_TARGET:
  		case EXPR_KIND_UPDATE_SOURCE:
  		case EXPR_KIND_UPDATE_TARGET:
  			errkind = true;
  			break;
  		case EXPR_KIND_GROUP_BY:
  			errkind = true;
  			break;
  		case EXPR_KIND_ORDER_BY:
  			/* okay */
  			break;
  		case EXPR_KIND_DISTINCT_ON:
  			/* okay */
  			break;
  		case EXPR_KIND_LIMIT:
  		case EXPR_KIND_OFFSET:
  			errkind = true;
  			break;
  		case EXPR_KIND_RETURNING:
  			errkind = true;
  			break;
  		case EXPR_KIND_VALUES:
  		case EXPR_KIND_VALUES_SINGLE:
  			errkind = true;
  			break;
  		case EXPR_KIND_CHECK_CONSTRAINT:
  		case EXPR_KIND_DOMAIN_CHECK:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in check constraints");
  			else
  				err = _("grouping operations are not allowed in check constraints");
  
  			break;
  		case EXPR_KIND_COLUMN_DEFAULT:
  		case EXPR_KIND_FUNCTION_DEFAULT:
  
  			if (isAgg)
  				err = _("aggregate functions are not allowed in DEFAULT expressions");
  			else
  				err = _("grouping operations are not allowed in DEFAULT expressions");
  
  			break;
  		case EXPR_KIND_INDEX_EXPRESSION:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in index expressions");
  			else
  				err = _("grouping operations are not allowed in index expressions");
  
  			break;
  		case EXPR_KIND_INDEX_PREDICATE:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in index predicates");
  			else
  				err = _("grouping operations are not allowed in index predicates");
  
  			break;
  		case EXPR_KIND_ALTER_COL_TRANSFORM:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in transform expressions");
  			else
  				err = _("grouping operations are not allowed in transform expressions");
  
  			break;
  		case EXPR_KIND_EXECUTE_PARAMETER:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in EXECUTE parameters");
  			else
  				err = _("grouping operations are not allowed in EXECUTE parameters");
  
  			break;
  		case EXPR_KIND_TRIGGER_WHEN:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in trigger WHEN conditions");
  			else
  				err = _("grouping operations are not allowed in trigger WHEN conditions");
  
  			break;
  		case EXPR_KIND_PARTITION_BOUND:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in partition bound");
  			else
  				err = _("grouping operations are not allowed in partition bound");
  
  			break;
  		case EXPR_KIND_PARTITION_EXPRESSION:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in partition key expressions");
  			else
  				err = _("grouping operations are not allowed in partition key expressions");
  
  			break;
  		case EXPR_KIND_GENERATED_COLUMN:
  
  			if (isAgg)
  				err = _("aggregate functions are not allowed in column generation expressions");
  			else
  				err = _("grouping operations are not allowed in column generation expressions");
  
  			break;
  
  		case EXPR_KIND_CALL_ARGUMENT:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in CALL arguments");
  			else
  				err = _("grouping operations are not allowed in CALL arguments");
  
  			break;
  
  		case EXPR_KIND_COPY_WHERE:
  			if (isAgg)
  				err = _("aggregate functions are not allowed in COPY FROM WHERE conditions");
  			else
  				err = _("grouping operations are not allowed in COPY FROM WHERE conditions");
  
  			break;
  
  			/*
  			 * There is intentionally no default: case here, so that the
  			 * compiler will warn if we add a new ParseExprKind without
  			 * extending this switch.  If we do see an unrecognized value at
  			 * runtime, the behavior will be the same as for EXPR_KIND_OTHER,
  			 * which is sane anyway.
  			 */
  	}
  
  	if (err)
  		ereport(ERROR,
  				(errcode(ERRCODE_GROUPING_ERROR),
  				 errmsg_internal("%s", err),
  				 parser_errposition(pstate, location)));
  
  	if (errkind)
  	{
  		if (isAgg)
  			/* translator: %s is name of a SQL construct, eg GROUP BY */
  			err = _("aggregate functions are not allowed in %s");
  		else
  			/* translator: %s is name of a SQL construct, eg GROUP BY */
  			err = _("grouping operations are not allowed in %s");
  
  		ereport(ERROR,
  				(errcode(ERRCODE_GROUPING_ERROR),
  				 errmsg_internal(err,
  								 ParseExprKindName(pstate->p_expr_kind)),
  				 parser_errposition(pstate, location)));
  	}
  }
  
  /*
   * check_agg_arguments
   *	  Scan the arguments of an aggregate function to determine the
   *	  aggregate's semantic level (zero is the current select's level,
   *	  one is its parent, etc).
   *
   * The aggregate's level is the same as the level of the lowest-level variable
   * or aggregate in its aggregated arguments (including any ORDER BY columns)
   * or filter expression; or if it contains no variables at all, we presume it
   * to be local.
   *
   * Vars/Aggs in direct arguments are *not* counted towards determining the
   * agg's level, as those arguments aren't evaluated per-row but only
   * per-group, and so in some sense aren't really agg arguments.  However,
   * this can mean that we decide an agg is upper-level even when its direct
   * args contain lower-level Vars/Aggs, and that case has to be disallowed.
   * (This is a little strange, but the SQL standard seems pretty definite that
   * direct args are not to be considered when setting the agg's level.)
   *
   * We also take this opportunity to detect any aggregates or window functions
   * nested within the arguments.  We can throw error immediately if we find
   * a window function.  Aggregates are a bit trickier because it's only an
   * error if the inner aggregate is of the same semantic level as the outer,
   * which we can't know until we finish scanning the arguments.
   */
  static int
  check_agg_arguments(ParseState *pstate,
  					List *directargs,
  					List *args,
  					Expr *filter)
  {
  	int			agglevel;
  	check_agg_arguments_context context;
  
  	context.pstate = pstate;
  	context.min_varlevel = -1;	/* signifies nothing found yet */
  	context.min_agglevel = -1;
  	context.sublevels_up = 0;
  
  	(void) expression_tree_walker((Node *) args,
  								  check_agg_arguments_walker,
  								  (void *) &context);
  
  	(void) expression_tree_walker((Node *) filter,
  								  check_agg_arguments_walker,
  								  (void *) &context);
  
  	/*
  	 * If we found no vars nor aggs at all, it's a level-zero aggregate;
  	 * otherwise, its level is the minimum of vars or aggs.
  	 */
  	if (context.min_varlevel < 0)
  	{
  		if (context.min_agglevel < 0)
  			agglevel = 0;
  		else
  			agglevel = context.min_agglevel;
  	}
  	else if (context.min_agglevel < 0)
  		agglevel = context.min_varlevel;
  	else
  		agglevel = Min(context.min_varlevel, context.min_agglevel);
  
  	/*
  	 * If there's a nested aggregate of the same semantic level, complain.
  	 */
  	if (agglevel == context.min_agglevel)
  	{
  		int			aggloc;
  
  		aggloc = locate_agg_of_level((Node *) args, agglevel);
  		if (aggloc < 0)
  			aggloc = locate_agg_of_level((Node *) filter, agglevel);
  		ereport(ERROR,
  				(errcode(ERRCODE_GROUPING_ERROR),
  				 errmsg("aggregate function calls cannot be nested"),
  				 parser_errposition(pstate, aggloc)));
  	}
  
  	/*
  	 * Now check for vars/aggs in the direct arguments, and throw error if
  	 * needed.  Note that we allow a Var of the agg's semantic level, but not
  	 * an Agg of that level.  In principle such Aggs could probably be
  	 * supported, but it would create an ordering dependency among the
  	 * aggregates at execution time.  Since the case appears neither to be
  	 * required by spec nor particularly useful, we just treat it as a
  	 * nested-aggregate situation.
  	 */
  	if (directargs)
  	{
  		context.min_varlevel = -1;
  		context.min_agglevel = -1;
  		(void) expression_tree_walker((Node *) directargs,
  									  check_agg_arguments_walker,
  									  (void *) &context);
  		if (context.min_varlevel >= 0 && context.min_varlevel < agglevel)
  			ereport(ERROR,
  					(errcode(ERRCODE_GROUPING_ERROR),
  					 errmsg("outer-level aggregate cannot contain a lower-level variable in its direct arguments"),
  					 parser_errposition(pstate,
  										locate_var_of_level((Node *) directargs,
  															context.min_varlevel))));
  		if (context.min_agglevel >= 0 && context.min_agglevel <= agglevel)
  			ereport(ERROR,
  					(errcode(ERRCODE_GROUPING_ERROR),
  					 errmsg("aggregate function calls cannot be nested"),
  					 parser_errposition(pstate,
  										locate_agg_of_level((Node *) directargs,
  															context.min_agglevel))));
  	}
  	return agglevel;
  }
  
  static bool
  check_agg_arguments_walker(Node *node,
  						   check_agg_arguments_context *context)
  {
  	if (node == NULL)
  		return false;
  	if (IsA(node, Var))
  	{
  		int			varlevelsup = ((Var *) node)->varlevelsup;
  
  		/* convert levelsup to frame of reference of original query */
  		varlevelsup -= context->sublevels_up;
  		/* ignore local vars of subqueries */
  		if (varlevelsup >= 0)
  		{
  			if (context->min_varlevel < 0 ||
  				context->min_varlevel > varlevelsup)
  				context->min_varlevel = varlevelsup;
  		}
  		return false;
  	}
  	if (IsA(node, Aggref))
  	{
  		int			agglevelsup = ((Aggref *) node)->agglevelsup;
  
  		/* convert levelsup to frame of reference of original query */
  		agglevelsup -= context->sublevels_up;
  		/* ignore local aggs of subqueries */
  		if (agglevelsup >= 0)
  		{
  			if (context->min_agglevel < 0 ||
  				context->min_agglevel > agglevelsup)
  				context->min_agglevel = agglevelsup;
  		}
  		/* no need to examine args of the inner aggregate */
  		return false;
  	}
  	if (IsA(node, GroupingFunc))
  	{
  		int			agglevelsup = ((GroupingFunc *) node)->agglevelsup;
  
  		/* convert levelsup to frame of reference of original query */
  		agglevelsup -= context->sublevels_up;
  		/* ignore local aggs of subqueries */
  		if (agglevelsup >= 0)
  		{
  			if (context->min_agglevel < 0 ||
  				context->min_agglevel > agglevelsup)
  				context->min_agglevel = agglevelsup;
  		}
  		/* Continue and descend into subtree */
  	}
  
  	/*
  	 * SRFs and window functions can be rejected immediately, unless we are
  	 * within a sub-select within the aggregate's arguments; in that case
  	 * they're OK.
  	 */
  	if (context->sublevels_up == 0)
  	{
  		if ((IsA(node, FuncExpr) &&((FuncExpr *) node)->funcretset) ||
  			(IsA(node, OpExpr) &&((OpExpr *) node)->opretset))
  			ereport(ERROR,
  					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
  					 errmsg("aggregate function calls cannot contain set-returning function calls"),
  					 errhint("You might be able to move the set-returning function into a LATERAL FROM item."),
  					 parser_errposition(context->pstate, exprLocation(node))));
  		if (IsA(node, WindowFunc))
  			ereport(ERROR,
  					(errcode(ERRCODE_GROUPING_ERROR),
  					 errmsg("aggregate function calls cannot contain window function calls"),
  					 parser_errposition(context->pstate,
  										((WindowFunc *) node)->location)));
  	}
  	if (IsA(node, Query))
  	{
  		/* Recurse into subselects */
  		bool		result;
  
  		context->sublevels_up++;
  		result = query_tree_walker((Query *) node,
  								   check_agg_arguments_walker,
  								   (void *) context,
  								   0);
  		context->sublevels_up--;
  		return result;
  	}
  
  	return expression_tree_walker(node,
  								  check_agg_arguments_walker,
  								  (void *) context);
  }
  
  /*
   * transformWindowFuncCall -
   *		Finish initial transformation of a window function call
   *
   * parse_func.c has recognized the function as a window function, and has set
   * up all the fields of the WindowFunc except winref.  Here we must (1) add
   * the WindowDef to the pstate (if not a duplicate of one already present) and
   * set winref to link to it; and (2) mark p_hasWindowFuncs true in the pstate.
   * Unlike aggregates, only the most closely nested pstate level need be
   * considered --- there are no "outer window functions" per SQL spec.
   */
  void
  transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
  						WindowDef *windef)
  {
  	const char *err;
  	bool		errkind;
  
  	/*
  	 * A window function call can't contain another one (but aggs are OK). XXX
  	 * is this required by spec, or just an unimplemented feature?
  	 *
  	 * Note: we don't need to check the filter expression here, because the
  	 * context checks done below and in transformAggregateCall would have
  	 * already rejected any window funcs or aggs within the filter.
  	 */
  	if (pstate->p_hasWindowFuncs &&
  		contain_windowfuncs((Node *) wfunc->args))
  		ereport(ERROR,
  				(errcode(ERRCODE_WINDOWING_ERROR),
  				 errmsg("window function calls cannot be nested"),
  				 parser_errposition(pstate,
  									locate_windowfunc((Node *) wfunc->args))));
  
  	/*
  	 * Check to see if the window function is in an invalid place within the
  	 * query.
  	 *
  	 * For brevity we support two schemes for reporting an error here: set
  	 * "err" to a custom message, or set "errkind" true if the error context
  	 * is sufficiently identified by what ParseExprKindName will return, *and*
  	 * what it will return is just a SQL keyword.  (Otherwise, use a custom
  	 * message to avoid creating translation problems.)
  	 */
  	err = NULL;
  	errkind = false;
  	switch (pstate->p_expr_kind)
  	{
  		case EXPR_KIND_NONE:
  			Assert(false);		/* can't happen */
  			break;
  		case EXPR_KIND_OTHER:
  			/* Accept window func here; caller must throw error if wanted */
  			break;
  		case EXPR_KIND_JOIN_ON:
  		case EXPR_KIND_JOIN_USING:
  			err = _("window functions are not allowed in JOIN conditions");
  			break;
  		case EXPR_KIND_FROM_SUBSELECT:
  			/* can't get here, but just in case, throw an error */
  			errkind = true;
  			break;
  		case EXPR_KIND_FROM_FUNCTION:
  			err = _("window functions are not allowed in functions in FROM");
  			break;
  		case EXPR_KIND_WHERE:
  			errkind = true;
  			break;
  		case EXPR_KIND_POLICY:
  			err = _("window functions are not allowed in policy expressions");
  			break;
  		case EXPR_KIND_HAVING:
  			errkind = true;
  			break;
  		case EXPR_KIND_FILTER:
  			errkind = true;
  			break;
  		case EXPR_KIND_WINDOW_PARTITION:
  		case EXPR_KIND_WINDOW_ORDER:
  		case EXPR_KIND_WINDOW_FRAME_RANGE:
  		case EXPR_KIND_WINDOW_FRAME_ROWS:
  		case EXPR_KIND_WINDOW_FRAME_GROUPS:
  			err = _("window functions are not allowed in window definitions");
  			break;
  		case EXPR_KIND_SELECT_TARGET:
  			/* okay */
  			break;
  		case EXPR_KIND_INSERT_TARGET:
  		case EXPR_KIND_UPDATE_SOURCE:
  		case EXPR_KIND_UPDATE_TARGET:
  			errkind = true;
  			break;
  		case EXPR_KIND_GROUP_BY:
  			errkind = true;
  			break;
  		case EXPR_KIND_ORDER_BY:
  			/* okay */
  			break;
  		case EXPR_KIND_DISTINCT_ON:
  			/* okay */
  			break;
  		case EXPR_KIND_LIMIT:
  		case EXPR_KIND_OFFSET:
  			errkind = true;
  			break;
  		case EXPR_KIND_RETURNING:
  			errkind = true;
  			break;
  		case EXPR_KIND_VALUES:
  		case EXPR_KIND_VALUES_SINGLE:
  			errkind = true;
  			break;
  		case EXPR_KIND_CHECK_CONSTRAINT:
  		case EXPR_KIND_DOMAIN_CHECK:
  			err = _("window functions are not allowed in check constraints");
  			break;
  		case EXPR_KIND_COLUMN_DEFAULT:
  		case EXPR_KIND_FUNCTION_DEFAULT:
  			err = _("window functions are not allowed in DEFAULT expressions");
  			break;
  		case EXPR_KIND_INDEX_EXPRESSION:
  			err = _("window functions are not allowed in index expressions");
  			break;
  		case EXPR_KIND_INDEX_PREDICATE:
  			err = _("window functions are not allowed in index predicates");
  			break;
  		case EXPR_KIND_ALTER_COL_TRANSFORM:
  			err = _("window functions are not allowed in transform expressions");
  			break;
  		case EXPR_KIND_EXECUTE_PARAMETER:
  			err = _("window functions are not allowed in EXECUTE parameters");
  			break;
  		case EXPR_KIND_TRIGGER_WHEN:
  			err = _("window functions are not allowed in trigger WHEN conditions");
  			break;
  		case EXPR_KIND_PARTITION_BOUND:
  			err = _("window functions are not allowed in partition bound");
  			break;
  		case EXPR_KIND_PARTITION_EXPRESSION:
  			err = _("window functions are not allowed in partition key expressions");
  			break;
  		case EXPR_KIND_CALL_ARGUMENT:
  			err = _("window functions are not allowed in CALL arguments");
  			break;
  		case EXPR_KIND_COPY_WHERE:
  			err = _("window functions are not allowed in COPY FROM WHERE conditions");
  			break;
  		case EXPR_KIND_GENERATED_COLUMN:
  			err = _("window functions are not allowed in column generation expressions");
  			break;
  
  			/*
  			 * There is intentionally no default: case here, so that the
  			 * compiler will warn if we add a new ParseExprKind without
  			 * extending this switch.  If we do see an unrecognized value at
  			 * runtime, the behavior will be the same as for EXPR_KIND_OTHER,
  			 * which is sane anyway.
  			 */
  	}
  	if (err)
  		ereport(ERROR,
  				(errcode(ERRCODE_WINDOWING_ERROR),
  				 errmsg_internal("%s", err),
  				 parser_errposition(pstate, wfunc->location)));
  	if (errkind)
  		ereport(ERROR,
  				(errcode(ERRCODE_WINDOWING_ERROR),
  		/* translator: %s is name of a SQL construct, eg GROUP BY */
  				 errmsg("window functions are not allowed in %s",
  						ParseExprKindName(pstate->p_expr_kind)),
  				 parser_errposition(pstate, wfunc->location)));
  
  	/*
  	 * If the OVER clause just specifies a window name, find that WINDOW
  	 * clause (which had better be present).  Otherwise, try to match all the
  	 * properties of the OVER clause, and make a new entry in the p_windowdefs
  	 * list if no luck.
  	 */
  	if (windef->name)
  	{
  		Index		winref = 0;
  		ListCell   *lc;
  
  		Assert(windef->refname == NULL &&
  			   windef->partitionClause == NIL &&
  			   windef->orderClause == NIL &&
  			   windef->frameOptions == FRAMEOPTION_DEFAULTS);
  
  		foreach(lc, pstate->p_windowdefs)
  		{
  			WindowDef  *refwin = (WindowDef *) lfirst(lc);
  
  			winref++;
  			if (refwin->name && strcmp(refwin->name, windef->name) == 0)
  			{
  				wfunc->winref = winref;
  				break;
  			}
  		}
  		if (lc == NULL)			/* didn't find it? */
  			ereport(ERROR,
  					(errcode(ERRCODE_UNDEFINED_OBJECT),
  					 errmsg("window \"%s\" does not exist", windef->name),
  					 parser_errposition(pstate, windef->location)));
  	}
  	else
  	{
  		Index		winref = 0;
  		ListCell   *lc;
  
  		foreach(lc, pstate->p_windowdefs)
  		{
  			WindowDef  *refwin = (WindowDef *) lfirst(lc);
  
  			winref++;
  			if (refwin->refname && windef->refname &&
  				strcmp(refwin->refname, windef->refname) == 0)
  				 /* matched on refname */ ;
  			else if (!refwin->refname && !windef->refname)
  				 /* matched, no refname */ ;
  			else
  				continue;
  			if (equal(refwin->partitionClause, windef->partitionClause) &&
  				equal(refwin->orderClause, windef->orderClause) &&
  				refwin->frameOptions == windef->frameOptions &&
  				equal(refwin->startOffset, windef->startOffset) &&
  				equal(refwin->endOffset, windef->endOffset))
  			{
  				/* found a duplicate window specification */
  				wfunc->winref = winref;
  				break;
  			}
  		}
  		if (lc == NULL)			/* didn't find it? */
  		{
  			pstate->p_windowdefs = lappend(pstate->p_windowdefs, windef);
  			wfunc->winref = list_length(pstate->p_windowdefs);
  		}
  	}
  
  	pstate->p_hasWindowFuncs = true;
  }
  
  /*
   * parseCheckAggregates
   *	Check for aggregates where they shouldn't be and improper grouping.
   *	This function should be called after the target list and qualifications
   *	are finalized.
   *
   *	Misplaced aggregates are now mostly detected in transformAggregateCall,
   *	but it seems more robust to check for aggregates in recursive queries
   *	only after everything is finalized.  In any case it's hard to detect
   *	improper grouping on-the-fly, so we have to make another pass over the
   *	query for that.
   */
  void
  parseCheckAggregates(ParseState *pstate, Query *qry)
  {
  	List	   *gset_common = NIL;
  	List	   *groupClauses = NIL;
  	List	   *groupClauseCommonVars = NIL;
  	bool		have_non_var_grouping;
  	List	   *func_grouped_rels = NIL;
  	ListCell   *l;
  	bool		hasJoinRTEs;
  	bool		hasSelfRefRTEs;
  	Node	   *clause;
  
  	/* This should only be called if we found aggregates or grouping */
  	Assert(pstate->p_hasAggs || qry->groupClause || qry->havingQual || qry->groupingSets);
  
  	/*
  	 * If we have grouping sets, expand them and find the intersection of all
  	 * sets.
  	 */
  	if (qry->groupingSets)
  	{
  		/*
  		 * The limit of 4096 is arbitrary and exists simply to avoid resource
  		 * issues from pathological constructs.
  		 */
  		List	   *gsets = expand_grouping_sets(qry->groupingSets, 4096);
  
  		if (!gsets)
  			ereport(ERROR,
  					(errcode(ERRCODE_STATEMENT_TOO_COMPLEX),
  					 errmsg("too many grouping sets present (maximum 4096)"),
  					 parser_errposition(pstate,
  										qry->groupClause
  										? exprLocation((Node *) qry->groupClause)
  										: exprLocation((Node *) qry->groupingSets))));
  
  		/*
  		 * The intersection will often be empty, so help things along by
  		 * seeding the intersect with the smallest set.
  		 */
  		gset_common = linitial(gsets);
  
  		if (gset_common)
  		{
  			for_each_cell(l, gsets, list_second_cell(gsets))
  			{
  				gset_common = list_intersection_int(gset_common, lfirst(l));
  				if (!gset_common)
  					break;
  			}
  		}
  
  		/*
  		 * If there was only one grouping set in the expansion, AND if the
  		 * groupClause is non-empty (meaning that the grouping set is not
  		 * empty either), then we can ditch the grouping set and pretend we
  		 * just had a normal GROUP BY.
  		 */
  		if (list_length(gsets) == 1 && qry->groupClause)
  			qry->groupingSets = NIL;
  	}
  
  	/*
  	 * Scan the range table to see if there are JOIN or self-reference CTE
  	 * entries.  We'll need this info below.
  	 */
  	hasJoinRTEs = hasSelfRefRTEs = false;
  	foreach(l, pstate->p_rtable)
  	{
  		RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
  
  		if (rte->rtekind == RTE_JOIN)
  			hasJoinRTEs = true;
  		else if (rte->rtekind == RTE_CTE && rte->self_reference)
  			hasSelfRefRTEs = true;
  	}
  
  	/*
  	 * Build a list of the acceptable GROUP BY expressions for use by
  	 * check_ungrouped_columns().
  	 *
  	 * We get the TLE, not just the expr, because GROUPING wants to know the
  	 * sortgroupref.
  	 */
  	foreach(l, qry->groupClause)
  	{
  		SortGroupClause *grpcl = (SortGroupClause *) lfirst(l);
  		TargetEntry *expr;
  
  		expr = get_sortgroupclause_tle(grpcl, qry->targetList);
  		if (expr == NULL)
  			continue;			/* probably cannot happen */
  
  		groupClauses = lappend(groupClauses, expr);
  	}
  
  	/*
  	 * If there are join alias vars involved, we have to flatten them to the
  	 * underlying vars, so that aliased and unaliased vars will be correctly
  	 * taken as equal.  We can skip the expense of doing this if no rangetable
  	 * entries are RTE_JOIN kind.
  	 */
  	if (hasJoinRTEs)
  		groupClauses = (List *) flatten_join_alias_vars(qry,
  														(Node *) groupClauses);
  
  	/*
  	 * Detect whether any of the grouping expressions aren't simple Vars; if
  	 * they're all Vars then we don't have to work so hard in the recursive
  	 * scans.  (Note we have to flatten aliases before this.)
  	 *
  	 * Track Vars that are included in all grouping sets separately in
  	 * groupClauseCommonVars, since these are the only ones we can use to
  	 * check for functional dependencies.
  	 */
  	have_non_var_grouping = false;
  	foreach(l, groupClauses)
  	{
  		TargetEntry *tle = lfirst(l);
  
  		if (!IsA(tle->expr, Var))
  		{
  			have_non_var_grouping = true;
  		}
  		else if (!qry->groupingSets ||
  				 list_member_int(gset_common, tle->ressortgroupref))
  		{
  			groupClauseCommonVars = lappend(groupClauseCommonVars, tle->expr);
  		}
  	}
  
  	/*
  	 * Check the targetlist and HAVING clause for ungrouped variables.
  	 *
  	 * Note: because we check resjunk tlist elements as well as regular ones,
  	 * this will also find ungrouped variables that came from ORDER BY and
  	 * WINDOW clauses.  For that matter, it's also going to examine the
  	 * grouping expressions themselves --- but they'll all pass the test ...
  	 *
  	 * We also finalize GROUPING expressions, but for that we need to traverse
  	 * the original (unflattened) clause in order to modify nodes.
  	 */
  	clause = (Node *) qry->targetList;
  	finalize_grouping_exprs(clause, pstate, qry,
  							groupClauses, hasJoinRTEs,
  							have_non_var_grouping);
  	if (hasJoinRTEs)
  		clause = flatten_join_alias_vars(qry, clause);
  	check_ungrouped_columns(clause, pstate, qry,
  							groupClauses, groupClauseCommonVars,
  							have_non_var_grouping,
  							&func_grouped_rels);
  
  	clause = (Node *) qry->havingQual;
  	finalize_grouping_exprs(clause, pstate, qry,
  							groupClauses, hasJoinRTEs,
  							have_non_var_grouping);
  	if (hasJoinRTEs)
  		clause = flatten_join_alias_vars(qry, clause);
  	check_ungrouped_columns(clause, pstate, qry,
  							groupClauses, groupClauseCommonVars,
  							have_non_var_grouping,
  							&func_grouped_rels);
  
  	/*
  	 * Per spec, aggregates can't appear in a recursive term.
  	 */
  	if (pstate->p_hasAggs && hasSelfRefRTEs)
  		ereport(ERROR,
  				(errcode(ERRCODE_INVALID_RECURSION),
  				 errmsg("aggregate functions are not allowed in a recursive query's recursive term"),
  				 parser_errposition(pstate,
  									locate_agg_of_level((Node *) qry, 0))));
  }
  
  /*
   * check_ungrouped_columns -
   *	  Scan the given expression tree for ungrouped variables (variables
   *	  that are not listed in the groupClauses list and are not within
   *	  the arguments of aggregate functions).  Emit a suitable error message
   *	  if any are found.
   *
   * NOTE: we assume that the given clause has been transformed suitably for
   * parser output.  This means we can use expression_tree_walker.
   *
   * NOTE: we recognize grouping expressions in the main query, but only
   * grouping Vars in subqueries.  For example, this will be rejected,
   * although it could be allowed:
   *		SELECT
   *			(SELECT x FROM bar where y = (foo.a + foo.b))
   *		FROM foo
   *		GROUP BY a + b;
   * The difficulty is the need to account for different sublevels_up.
   * This appears to require a whole custom version of equal(), which is
   * way more pain than the feature seems worth.
   */
  static void
  check_ungrouped_columns(Node *node, ParseState *pstate, Query *qry,
  						List *groupClauses, List *groupClauseCommonVars,
  						bool have_non_var_grouping,
  						List **func_grouped_rels)
  {
  	check_ungrouped_columns_context context;
  
  	context.pstate = pstate;
  	context.qry = qry;
  	context.hasJoinRTEs = false;	/* assume caller flattened join Vars */
  	context.groupClauses = groupClauses;
  	context.groupClauseCommonVars = groupClauseCommonVars;
  	context.have_non_var_grouping = have_non_var_grouping;
  	context.func_grouped_rels = func_grouped_rels;
  	context.sublevels_up = 0;
  	context.in_agg_direct_args = false;
  	check_ungrouped_columns_walker(node, &context);
  }
  
  static bool
  check_ungrouped_columns_walker(Node *node,
  							   check_ungrouped_columns_context *context)
  {
  	ListCell   *gl;
  
  	if (node == NULL)
  		return false;
  	if (IsA(node, Const) ||
  		IsA(node, Param))
  		return false;			/* constants are always acceptable */
  
  	if (IsA(node, Aggref))
  	{
  		Aggref	   *agg = (Aggref *) node;
  
  		if ((int) agg->agglevelsup == context->sublevels_up)
  		{
  			/*
  			 * If we find an aggregate call of the original level, do not
  			 * recurse into its normal arguments, ORDER BY arguments, or
  			 * filter; ungrouped vars there are not an error.  But we should
  			 * check direct arguments as though they weren't in an aggregate.
  			 * We set a special flag in the context to help produce a useful
  			 * error message for ungrouped vars in direct arguments.
  			 */
  			bool		result;
  
  			Assert(!context->in_agg_direct_args);
  			context->in_agg_direct_args = true;
  			result = check_ungrouped_columns_walker((Node *) agg->aggdirectargs,
  													context);
  			context->in_agg_direct_args = false;
  			return result;
  		}
  
  		/*
  		 * We can skip recursing into aggregates of higher levels altogether,
  		 * since they could not possibly contain Vars of concern to us (see
  		 * transformAggregateCall).  We do need to look at aggregates of lower
  		 * levels, however.
  		 */
  		if ((int) agg->agglevelsup > context->sublevels_up)
  			return false;
  	}
  
  	if (IsA(node, GroupingFunc))
  	{
  		GroupingFunc *grp = (GroupingFunc *) node;
  
  		/* handled GroupingFunc separately, no need to recheck at this level */
  
  		if ((int) grp->agglevelsup >= context->sublevels_up)
  			return false;
  	}
  
  	/*
  	 * If we have any GROUP BY items that are not simple Vars, check to see if
  	 * subexpression as a whole matches any GROUP BY item. We need to do this
  	 * at every recursion level so that we recognize GROUPed-BY expressions
  	 * before reaching variables within them. But this only works at the outer
  	 * query level, as noted above.
  	 */
  	if (context->have_non_var_grouping && context->sublevels_up == 0)
  	{
  		foreach(gl, context->groupClauses)
  		{
  			TargetEntry *tle = lfirst(gl);
  
  			if (equal(node, tle->expr))
  				return false;	/* acceptable, do not descend more */
  		}
  	}
  
  	/*
  	 * If we have an ungrouped Var of the original query level, we have a
  	 * failure.  Vars below the original query level are not a problem, and
  	 * neither are Vars from above it.  (If such Vars are ungrouped as far as
  	 * their own query level is concerned, that's someone else's problem...)
  	 */
  	if (IsA(node, Var))
  	{
  		Var		   *var = (Var *) node;
  		RangeTblEntry *rte;
  		char	   *attname;
  
  		if (var->varlevelsup != context->sublevels_up)
  			return false;		/* it's not local to my query, ignore */
  
  		/*
  		 * Check for a match, if we didn't do it above.
  		 */
  		if (!context->have_non_var_grouping || context->sublevels_up != 0)
  		{
  			foreach(gl, context->groupClauses)
  			{
  				Var		   *gvar = (Var *) ((TargetEntry *) lfirst(gl))->expr;
  
  				if (IsA(gvar, Var) &&
  					gvar->varno == var->varno &&
  					gvar->varattno == var->varattno &&
  					gvar->varlevelsup == 0)
  					return false;	/* acceptable, we're okay */
  			}
  		}
  
  		/*
  		 * Check whether the Var is known functionally dependent on the GROUP
  		 * BY columns.  If so, we can allow the Var to be used, because the
  		 * grouping is really a no-op for this table.  However, this deduction
  		 * depends on one or more constraints of the table, so we have to add
  		 * those constraints to the query's constraintDeps list, because it's
  		 * not semantically valid anymore if the constraint(s) get dropped.
  		 * (Therefore, this check must be the last-ditch effort before raising
  		 * error: we don't want to add dependencies unnecessarily.)
  		 *
  		 * Because this is a pretty expensive check, and will have the same
  		 * outcome for all columns of a table, we remember which RTEs we've
  		 * already proven functional dependency for in the func_grouped_rels
  		 * list.  This test also prevents us from adding duplicate entries to
  		 * the constraintDeps list.
  		 */
  		if (list_member_int(*context->func_grouped_rels, var->varno))
  			return false;		/* previously proven acceptable */
  
  		Assert(var->varno > 0 &&
  			   (int) var->varno <= list_length(context->pstate->p_rtable));
  		rte = rt_fetch(var->varno, context->pstate->p_rtable);
  		if (rte->rtekind == RTE_RELATION)
  		{
  			if (check_functional_grouping(rte->relid,
  										  var->varno,
  										  0,
  										  context->groupClauseCommonVars,
  										  &context->qry->constraintDeps))
  			{
  				*context->func_grouped_rels =
  					lappend_int(*context->func_grouped_rels, var->varno);
  				return false;	/* acceptable */
  			}
  		}
  
  		/* Found an ungrouped local variable; generate error message */
  		attname = get_rte_attribute_name(rte, var->varattno);
  		if (context->sublevels_up == 0)
  			ereport(ERROR,
  					(errcode(ERRCODE_GROUPING_ERROR),
  					 errmsg("column \"%s.%s\" must appear in the GROUP BY clause or be used in an aggregate function",
  							rte->eref->aliasname, attname),
  					 context->in_agg_direct_args ?
  					 errdetail("Direct arguments of an ordered-set aggregate must use only grouped columns.") : 0,
  					 parser_errposition(context->pstate, var->location)));
  		else
  			ereport(ERROR,
  					(errcode(ERRCODE_GROUPING_ERROR),
  					 errmsg("subquery uses ungrouped column \"%s.%s\" from outer query",
  							rte->eref->aliasname, attname),
  					 parser_errposition(context->pstate, var->location)));
  	}
  
  	if (IsA(node, Query))
  	{
  		/* Recurse into subselects */
  		bool		result;
  
  		context->sublevels_up++;
  		result = query_tree_walker((Query *) node,
  								   check_ungrouped_columns_walker,
  								   (void *) context,
  								   0);
  		context->sublevels_up--;
  		return result;
  	}
  	return expression_tree_walker(node, check_ungrouped_columns_walker,
  								  (void *) context);
  }
  
  /*
   * finalize_grouping_exprs -
   *	  Scan the given expression tree for GROUPING() and related calls,
   *	  and validate and process their arguments.
   *
   * This is split out from check_ungrouped_columns above because it needs
   * to modify the nodes (which it does in-place, not via a mutator) while
   * check_ungrouped_columns may see only a copy of the original thanks to
   * flattening of join alias vars. So here, we flatten each individual
   * GROUPING argument as we see it before comparing it.
   */
  static void
  finalize_grouping_exprs(Node *node, ParseState *pstate, Query *qry,
  						List *groupClauses, bool hasJoinRTEs,
  						bool have_non_var_grouping)
  {
  	check_ungrouped_columns_context context;
  
  	context.pstate = pstate;
  	context.qry = qry;
  	context.hasJoinRTEs = hasJoinRTEs;
  	context.groupClauses = groupClauses;
  	context.groupClauseCommonVars = NIL;
  	context.have_non_var_grouping = have_non_var_grouping;
  	context.func_grouped_rels = NULL;
  	context.sublevels_up = 0;
  	context.in_agg_direct_args = false;
  	finalize_grouping_exprs_walker(node, &context);
  }
  
  static bool
  finalize_grouping_exprs_walker(Node *node,
  							   check_ungrouped_columns_context *context)
  {
  	ListCell   *gl;
  
  	if (node == NULL)
  		return false;
  	if (IsA(node, Const) ||
  		IsA(node, Param))
  		return false;			/* constants are always acceptable */
  
  	if (IsA(node, Aggref))
  	{
  		Aggref	   *agg = (Aggref *) node;
  
  		if ((int) agg->agglevelsup == context->sublevels_up)
  		{
  			/*
  			 * If we find an aggregate call of the original level, do not
  			 * recurse into its normal arguments, ORDER BY arguments, or
  			 * filter; GROUPING exprs of this level are not allowed there. But
  			 * check direct arguments as though they weren't in an aggregate.
  			 */
  			bool		result;
  
  			Assert(!context->in_agg_direct_args);
  			context->in_agg_direct_args = true;
  			result = finalize_grouping_exprs_walker((Node *) agg->aggdirectargs,
  													context);
  			context->in_agg_direct_args = false;
  			return result;
  		}
  
  		/*
  		 * We can skip recursing into aggregates of higher levels altogether,
  		 * since they could not possibly contain exprs of concern to us (see
  		 * transformAggregateCall).  We do need to look at aggregates of lower
  		 * levels, however.
  		 */
  		if ((int) agg->agglevelsup > context->sublevels_up)
  			return false;
  	}
  
  	if (IsA(node, GroupingFunc))
  	{
  		GroupingFunc *grp = (GroupingFunc *) node;
  
  		/*
  		 * We only need to check GroupingFunc nodes at the exact level to
  		 * which they belong, since they cannot mix levels in arguments.
  		 */
  
  		if ((int) grp->agglevelsup == context->sublevels_up)
  		{
  			ListCell   *lc;
  			List	   *ref_list = NIL;
  
  			foreach(lc, grp->args)
  			{
  				Node	   *expr = lfirst(lc);
  				Index		ref = 0;
  
  				if (context->hasJoinRTEs)
  					expr = flatten_join_alias_vars(context->qry, expr);
  
  				/*
  				 * Each expression must match a grouping entry at the current
  				 * query level. Unlike the general expression case, we don't
  				 * allow functional dependencies or outer references.
  				 */
  
  				if (IsA(expr, Var))
  				{
  					Var		   *var = (Var *) expr;
  
  					if (var->varlevelsup == context->sublevels_up)
  					{
  						foreach(gl, context->groupClauses)
  						{
  							TargetEntry *tle = lfirst(gl);
  							Var		   *gvar = (Var *) tle->expr;
  
  							if (IsA(gvar, Var) &&
  								gvar->varno == var->varno &&
  								gvar->varattno == var->varattno &&
  								gvar->varlevelsup == 0)
  							{
  								ref = tle->ressortgroupref;
  								break;
  							}
  						}
  					}
  				}
  				else if (context->have_non_var_grouping &&
  						 context->sublevels_up == 0)
  				{
  					foreach(gl, context->groupClauses)
  					{
  						TargetEntry *tle = lfirst(gl);
  
  						if (equal(expr, tle->expr))
  						{
  							ref = tle->ressortgroupref;
  							break;
  						}
  					}
  				}
  
  				if (ref == 0)
  					ereport(ERROR,
  							(errcode(ERRCODE_GROUPING_ERROR),
  							 errmsg("arguments to GROUPING must be grouping expressions of the associated query level"),
  							 parser_errposition(context->pstate,
  												exprLocation(expr))));
  
  				ref_list = lappend_int(ref_list, ref);
  			}
  
  			grp->refs = ref_list;
  		}
  
  		if ((int) grp->agglevelsup > context->sublevels_up)
  			return false;
  	}
  
  	if (IsA(node, Query))
  	{
  		/* Recurse into subselects */
  		bool		result;
  
  		context->sublevels_up++;
  		result = query_tree_walker((Query *) node,
  								   finalize_grouping_exprs_walker,
  								   (void *) context,
  								   0);
  		context->sublevels_up--;
  		return result;
  	}
  	return expression_tree_walker(node, finalize_grouping_exprs_walker,
  								  (void *) context);
  }
  
  
  /*
   * Given a GroupingSet node, expand it and return a list of lists.
   *
   * For EMPTY nodes, return a list of one empty list.
   *
   * For SIMPLE nodes, return a list of one list, which is the node content.
   *
   * For CUBE and ROLLUP nodes, return a list of the expansions.
   *
   * For SET nodes, recursively expand contained CUBE and ROLLUP.
   */
  static List *
  expand_groupingset_node(GroupingSet *gs)
  {
  	List	   *result = NIL;
  
  	switch (gs->kind)
  	{
  		case GROUPING_SET_EMPTY:
  			result = list_make1(NIL);
  			break;
  
  		case GROUPING_SET_SIMPLE:
  			result = list_make1(gs->content);
  			break;
  
  		case GROUPING_SET_ROLLUP:
  			{
  				List	   *rollup_val = gs->content;
  				ListCell   *lc;
  				int			curgroup_size = list_length(gs->content);
  
  				while (curgroup_size > 0)
  				{
  					List	   *current_result = NIL;
  					int			i = curgroup_size;
  
  					foreach(lc, rollup_val)
  					{
  						GroupingSet *gs_current = (GroupingSet *) lfirst(lc);
  
  						Assert(gs_current->kind == GROUPING_SET_SIMPLE);
  
  						current_result
  							= list_concat(current_result,
  										  list_copy(gs_current->content));
  
  						/* If we are done with making the current group, break */
  						if (--i == 0)
  							break;
  					}
  
  					result = lappend(result, current_result);
  					--curgroup_size;
  				}
  
  				result = lappend(result, NIL);
  			}
  			break;
  
  		case GROUPING_SET_CUBE:
  			{
  				List	   *cube_list = gs->content;
  				int			number_bits = list_length(cube_list);
  				uint32		num_sets;
  				uint32		i;
  
  				/* parser should cap this much lower */
  				Assert(number_bits < 31);
  
  				num_sets = (1U << number_bits);
  
  				for (i = 0; i < num_sets; i++)
  				{
  					List	   *current_result = NIL;
  					ListCell   *lc;
  					uint32		mask = 1U;
  
  					foreach(lc, cube_list)
  					{
  						GroupingSet *gs_current = (GroupingSet *) lfirst(lc);
  
  						Assert(gs_current->kind == GROUPING_SET_SIMPLE);
  
  						if (mask & i)
  						{
  							current_result
  								= list_concat(current_result,
  											  list_copy(gs_current->content));
  						}
  
  						mask <<= 1;
  					}
  
  					result = lappend(result, current_result);
  				}
  			}
  			break;
  
  		case GROUPING_SET_SETS:
  			{
  				ListCell   *lc;
  
  				foreach(lc, gs->content)
  				{
  					List	   *current_result = expand_groupingset_node(lfirst(lc));
  
  					result = list_concat(result, current_result);
  				}
  			}
  			break;
  	}
  
  	return result;
  }
  
  /* list_sort comparator to sort sub-lists by length */
  static int
  cmp_list_len_asc(const ListCell *a, const ListCell *b)
  {
  	int			la = list_length((const List *) lfirst(a));
  	int			lb = list_length((const List *) lfirst(b));
  
  	return (la > lb) ? 1 : (la == lb) ? 0 : -1;
  }
  
  /*
   * Expand a groupingSets clause to a flat list of grouping sets.
   * The returned list is sorted by length, shortest sets first.
   *
   * This is mainly for the planner, but we use it here too to do
   * some consistency checks.
   */
  List *
  expand_grouping_sets(List *groupingSets, int limit)
  {
  	List	   *expanded_groups = NIL;
  	List	   *result = NIL;
  	double		numsets = 1;
  	ListCell   *lc;
  
  	if (groupingSets == NIL)
  		return NIL;
  
  	foreach(lc, groupingSets)
  	{
  		List	   *current_result = NIL;
  		GroupingSet *gs = lfirst(lc);
  
  		current_result = expand_groupingset_node(gs);
  
  		Assert(current_result != NIL);
  
  		numsets *= list_length(current_result);
  
  		if (limit >= 0 && numsets > limit)
  			return NIL;
  
  		expanded_groups = lappend(expanded_groups, current_result);
  	}
  
  	/*
  	 * Do cartesian product between sublists of expanded_groups. While at it,
  	 * remove any duplicate elements from individual grouping sets (we must
  	 * NOT change the number of sets though)
  	 */
  
  	foreach(lc, (List *) linitial(expanded_groups))
  	{
  		result = lappend(result, list_union_int(NIL, (List *) lfirst(lc)));
  	}
  
  	for_each_cell(lc, expanded_groups, list_second_cell(expanded_groups))
  	{
  		List	   *p = lfirst(lc);
  		List	   *new_result = NIL;
  		ListCell   *lc2;
  
  		foreach(lc2, result)
  		{
  			List	   *q = lfirst(lc2);
  			ListCell   *lc3;
  
  			foreach(lc3, p)
  			{
  				new_result = lappend(new_result,
  									 list_union_int(q, (List *) lfirst(lc3)));
  			}
  		}
  		result = new_result;
  	}
  
  	/* Now sort the lists by length */
  	list_sort(result, cmp_list_len_asc);
  
  	return result;
  }
  
  /*
   * get_aggregate_argtypes
   *	Identify the specific datatypes passed to an aggregate call.
   *
   * Given an Aggref, extract the actual datatypes of the input arguments.
   * The input datatypes are reported in a way that matches up with the
   * aggregate's declaration, ie, any ORDER BY columns attached to a plain
   * aggregate are ignored, but we report both direct and aggregated args of
   * an ordered-set aggregate.
   *
   * Datatypes are returned into inputTypes[], which must reference an array
   * of length FUNC_MAX_ARGS.
   *
   * The function result is the number of actual arguments.
   */
  int
  get_aggregate_argtypes(Aggref *aggref, Oid *inputTypes)
  {
  	int			numArguments = 0;
  	ListCell   *lc;
  
  	Assert(list_length(aggref->aggargtypes) <= FUNC_MAX_ARGS);
  
  	foreach(lc, aggref->aggargtypes)
  	{
  		inputTypes[numArguments++] = lfirst_oid(lc);
  	}
  
  	return numArguments;
  }
  
  /*
   * resolve_aggregate_transtype
   *	Identify the transition state value's datatype for an aggregate call.
   *
   * This function resolves a polymorphic aggregate's state datatype.
   * It must be passed the aggtranstype from the aggregate's catalog entry,
   * as well as the actual argument types extracted by get_aggregate_argtypes.
   * (We could fetch pg_aggregate.aggtranstype internally, but all existing
   * callers already have the value at hand, so we make them pass it.)
   */
  Oid
  resolve_aggregate_transtype(Oid aggfuncid,
  							Oid aggtranstype,
  							Oid *inputTypes,
  							int numArguments)
  {
  	/* resolve actual type of transition state, if polymorphic */
  	if (IsPolymorphicType(aggtranstype))
  	{
  		/* have to fetch the agg's declared input types... */
  		Oid		   *declaredArgTypes;
  		int			agg_nargs;
  
  		(void) get_func_signature(aggfuncid, &declaredArgTypes, &agg_nargs);
  
  		/*
  		 * VARIADIC ANY aggs could have more actual than declared args, but
  		 * such extra args can't affect polymorphic type resolution.
  		 */
  		Assert(agg_nargs <= numArguments);
  
  		aggtranstype = enforce_generic_type_consistency(inputTypes,
  														declaredArgTypes,
  														agg_nargs,
  														aggtranstype,
  														false);
  		pfree(declaredArgTypes);
  	}
  	return aggtranstype;
  }
  
  /*
   * Create an expression tree for the transition function of an aggregate.
   * This is needed so that polymorphic functions can be used within an
   * aggregate --- without the expression tree, such functions would not know
   * the datatypes they are supposed to use.  (The trees will never actually
   * be executed, however, so we can skimp a bit on correctness.)
   *
   * agg_input_types and agg_state_type identifies the input types of the
   * aggregate.  These should be resolved to actual types (ie, none should
   * ever be ANYELEMENT etc).
   * agg_input_collation is the aggregate function's input collation.
   *
   * For an ordered-set aggregate, remember that agg_input_types describes
   * the direct arguments followed by the aggregated arguments.
   *
   * transfn_oid and invtransfn_oid identify the funcs to be called; the
   * latter may be InvalidOid, however if invtransfn_oid is set then
   * transfn_oid must also be set.
   *
   * Pointers to the constructed trees are returned into *transfnexpr,
   * *invtransfnexpr. If there is no invtransfn, the respective pointer is set
   * to NULL.  Since use of the invtransfn is optional, NULL may be passed for
   * invtransfnexpr.
   */
  void
  build_aggregate_transfn_expr(Oid *agg_input_types,
  							 int agg_num_inputs,
  							 int agg_num_direct_inputs,
  							 bool agg_variadic,
  							 Oid agg_state_type,
  							 Oid agg_input_collation,
  							 Oid transfn_oid,
  							 Oid invtransfn_oid,
  							 Expr **transfnexpr,
  							 Expr **invtransfnexpr)
  {
  	List	   *args;
  	FuncExpr   *fexpr;
  	int			i;
  
  	/*
  	 * Build arg list to use in the transfn FuncExpr node.
  	 */
  	args = list_make1(make_agg_arg(agg_state_type, agg_input_collation));
  
  	for (i = agg_num_direct_inputs; i < agg_num_inputs; i++)
  	{
  		args = lappend(args,
  					   make_agg_arg(agg_input_types[i], agg_input_collation));
  	}
  
  	fexpr = makeFuncExpr(transfn_oid,
  						 agg_state_type,
  						 args,
  						 InvalidOid,
  						 agg_input_collation,
  						 COERCE_EXPLICIT_CALL);
  	fexpr->funcvariadic = agg_variadic;
  	*transfnexpr = (Expr *) fexpr;
  
  	/*
  	 * Build invtransfn expression if requested, with same args as transfn
  	 */
  	if (invtransfnexpr != NULL)
  	{
  		if (OidIsValid(invtransfn_oid))
  		{
  			fexpr = makeFuncExpr(invtransfn_oid,
  								 agg_state_type,
  								 args,
  								 InvalidOid,
  								 agg_input_collation,
  								 COERCE_EXPLICIT_CALL);
  			fexpr->funcvariadic = agg_variadic;
  			*invtransfnexpr = (Expr *) fexpr;
  		}
  		else
  			*invtransfnexpr = NULL;
  	}
  }
  
  /*
   * Like build_aggregate_transfn_expr, but creates an expression tree for the
   * combine function of an aggregate, rather than the transition function.
   */
  void
  build_aggregate_combinefn_expr(Oid agg_state_type,
  							   Oid agg_input_collation,
  							   Oid combinefn_oid,
  							   Expr **combinefnexpr)
  {
  	Node	   *argp;
  	List	   *args;
  	FuncExpr   *fexpr;
  
  	/* combinefn takes two arguments of the aggregate state type */
  	argp = make_agg_arg(agg_state_type, agg_input_collation);
  
  	args = list_make2(argp, argp);
  
  	fexpr = makeFuncExpr(combinefn_oid,
  						 agg_state_type,
  						 args,
  						 InvalidOid,
  						 agg_input_collation,
  						 COERCE_EXPLICIT_CALL);
  	/* combinefn is currently never treated as variadic */
  	*combinefnexpr = (Expr *) fexpr;
  }
  
  /*
   * Like build_aggregate_transfn_expr, but creates an expression tree for the
   * serialization function of an aggregate.
   */
  void
  build_aggregate_serialfn_expr(Oid serialfn_oid,
  							  Expr **serialfnexpr)
  {
  	List	   *args;
  	FuncExpr   *fexpr;
  
  	/* serialfn always takes INTERNAL and returns BYTEA */
  	args = list_make1(make_agg_arg(INTERNALOID, InvalidOid));
  
  	fexpr = makeFuncExpr(serialfn_oid,
  						 BYTEAOID,
  						 args,
  						 InvalidOid,
  						 InvalidOid,
  						 COERCE_EXPLICIT_CALL);
  	*serialfnexpr = (Expr *) fexpr;
  }
  
  /*
   * Like build_aggregate_transfn_expr, but creates an expression tree for the
   * deserialization function of an aggregate.
   */
  void
  build_aggregate_deserialfn_expr(Oid deserialfn_oid,
  								Expr **deserialfnexpr)
  {
  	List	   *args;
  	FuncExpr   *fexpr;
  
  	/* deserialfn always takes BYTEA, INTERNAL and returns INTERNAL */
  	args = list_make2(make_agg_arg(BYTEAOID, InvalidOid),
  					  make_agg_arg(INTERNALOID, InvalidOid));
  
  	fexpr = makeFuncExpr(deserialfn_oid,
  						 INTERNALOID,
  						 args,
  						 InvalidOid,
  						 InvalidOid,
  						 COERCE_EXPLICIT_CALL);
  	*deserialfnexpr = (Expr *) fexpr;
  }
  
  /*
   * Like build_aggregate_transfn_expr, but creates an expression tree for the
   * final function of an aggregate, rather than the transition function.
   */
  void
  build_aggregate_finalfn_expr(Oid *agg_input_types,
  							 int num_finalfn_inputs,
  							 Oid agg_state_type,
  							 Oid agg_result_type,
  							 Oid agg_input_collation,
  							 Oid finalfn_oid,
  							 Expr **finalfnexpr)
  {
  	List	   *args;
  	int			i;
  
  	/*
  	 * Build expr tree for final function
  	 */
  	args = list_make1(make_agg_arg(agg_state_type, agg_input_collation));
  
  	/* finalfn may take additional args, which match agg's input types */
  	for (i = 0; i < num_finalfn_inputs - 1; i++)
  	{
  		args = lappend(args,
  					   make_agg_arg(agg_input_types[i], agg_input_collation));
  	}
  
  	*finalfnexpr = (Expr *) makeFuncExpr(finalfn_oid,
  										 agg_result_type,
  										 args,
  										 InvalidOid,
  										 agg_input_collation,
  										 COERCE_EXPLICIT_CALL);
  	/* finalfn is currently never treated as variadic */
  }
  
  /*
   * Convenience function to build dummy argument expressions for aggregates.
   *
   * We really only care that an aggregate support function can discover its
   * actual argument types at runtime using get_fn_expr_argtype(), so it's okay
   * to use Param nodes that don't correspond to any real Param.
   */
  static Node *
  make_agg_arg(Oid argtype, Oid argcollation)
  {
  	Param	   *argp = makeNode(Param);
  
  	argp->paramkind = PARAM_EXEC;
  	argp->paramid = -1;
  	argp->paramtype = argtype;
  	argp->paramtypmod = -1;
  	argp->paramcollid = argcollation;
  	argp->location = -1;
  	return (Node *) argp;
  }
  