• Tom Lane's avatar
    Extend the parser location infrastructure to include a location field in · a2794623
    Tom Lane authored
    most node types used in expression trees (both before and after parse
    analysis).  This allows us to place an error cursor in many situations
    where we formerly could not, because the information wasn't available
    beyond the very first level of parse analysis.  There's a fair amount
    of work still to be done to persuade individual ereport() calls to actually
    include an error location, but this gets the initdb-forcing part of the
    work out of the way; and the situation is already markedly better than
    before for complaints about unimplementable implicit casts, such as
    CASE and UNION constructs with incompatible alternative data types.
    Per my proposal of a few days ago.
    a2794623
rewriteManip.c 28.7 KB
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/*-------------------------------------------------------------------------
 *
 * rewriteManip.c
 *
 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.112 2008/08/28 23:09:48 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteManip.h"


typedef struct
{
	int			sublevels_up;
} contain_aggs_of_level_context;

static bool contain_aggs_of_level_walker(Node *node,
						contain_aggs_of_level_context *context);
static bool checkExprHasSubLink_walker(Node *node, void *context);
static Relids offset_relid_set(Relids relids, int offset);
static Relids adjust_relid_set(Relids relids, int oldrelid, int newrelid);


/*
 * checkExprHasAggs -
 *	Check if an expression contains an aggregate function call.
 */
bool
checkExprHasAggs(Node *node)
{
	return contain_aggs_of_level(node, 0);
}

/*
 * contain_aggs_of_level -
 *	Check if an expression contains an aggregate function call of a
 *	specified query level.
 *
 * The objective of this routine is to detect whether there are aggregates
 * belonging to the given query level.  Aggregates belonging to subqueries
 * or outer queries do NOT cause a true result.  We must recurse into
 * subqueries to detect outer-reference aggregates that logically belong to
 * the specified query level.
 */
bool
contain_aggs_of_level(Node *node, int levelsup)
{
	contain_aggs_of_level_context context;

	context.sublevels_up = levelsup;

	/*
	 * Must be prepared to start with a Query or a bare expression tree; if
	 * it's a Query, we don't want to increment sublevels_up.
	 */
	return query_or_expression_tree_walker(node,
										   contain_aggs_of_level_walker,
										   (void *) &context,
										   0);
}

static bool
contain_aggs_of_level_walker(Node *node,
							 contain_aggs_of_level_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Aggref))
	{
		if (((Aggref *) node)->agglevelsup == context->sublevels_up)
			return true;		/* abort the tree traversal and return true */
		/* else fall through to examine argument */
	}
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		bool		result;

		context->sublevels_up++;
		result = query_tree_walker((Query *) node,
								   contain_aggs_of_level_walker,
								   (void *) context, 0);
		context->sublevels_up--;
		return result;
	}
	return expression_tree_walker(node, contain_aggs_of_level_walker,
								  (void *) context);
}

/*
 * checkExprHasSubLink -
 *	Check if an expression contains a SubLink.
 */
bool
checkExprHasSubLink(Node *node)
{
	/*
	 * If a Query is passed, examine it --- but we need not recurse into
	 * sub-Queries.
	 */
	return query_or_expression_tree_walker(node,
										   checkExprHasSubLink_walker,
										   NULL,
										   QTW_IGNORE_RT_SUBQUERIES);
}

static bool
checkExprHasSubLink_walker(Node *node, void *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, SubLink))
		return true;			/* abort the tree traversal and return true */
	return expression_tree_walker(node, checkExprHasSubLink_walker, context);
}


/*
 * OffsetVarNodes - adjust Vars when appending one query's RT to another
 *
 * Find all Var nodes in the given tree with varlevelsup == sublevels_up,
 * and increment their varno fields (rangetable indexes) by 'offset'.
 * The varnoold fields are adjusted similarly.	Also, adjust other nodes
 * that contain rangetable indexes, such as RangeTblRef and JoinExpr.
 *
 * NOTE: although this has the form of a walker, we cheat and modify the
 * nodes in-place.	The given expression tree should have been copied
 * earlier to ensure that no unwanted side-effects occur!
 */

typedef struct
{
	int			offset;
	int			sublevels_up;
} OffsetVarNodes_context;

static bool
OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) node;

		if (var->varlevelsup == context->sublevels_up)
		{
			var->varno += context->offset;
			var->varnoold += context->offset;
		}
		return false;
	}
	if (IsA(node, CurrentOfExpr))
	{
		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;

		if (context->sublevels_up == 0)
			cexpr->cvarno += context->offset;
		return false;
	}
	if (IsA(node, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) node;

		if (context->sublevels_up == 0)
			rtr->rtindex += context->offset;
		/* the subquery itself is visited separately */
		return false;
	}
	if (IsA(node, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) node;

		if (context->sublevels_up == 0)
			j->rtindex += context->offset;
		/* fall through to examine children */
	}
	if (IsA(node, FlattenedSubLink))
	{
		FlattenedSubLink *fslink = (FlattenedSubLink *) node;

		if (context->sublevels_up == 0)
		{
			fslink->lefthand = offset_relid_set(fslink->lefthand,
												context->offset);
			fslink->righthand = offset_relid_set(fslink->righthand,
												 context->offset);
		}
		/* fall through to examine children */
	}
	if (IsA(node, AppendRelInfo))
	{
		AppendRelInfo *appinfo = (AppendRelInfo *) node;

		if (context->sublevels_up == 0)
		{
			appinfo->parent_relid += context->offset;
			appinfo->child_relid += context->offset;
		}
		/* fall through to examine children */
	}
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		bool		result;

		context->sublevels_up++;
		result = query_tree_walker((Query *) node, OffsetVarNodes_walker,
								   (void *) context, 0);
		context->sublevels_up--;
		return result;
	}
	return expression_tree_walker(node, OffsetVarNodes_walker,
								  (void *) context);
}

void
OffsetVarNodes(Node *node, int offset, int sublevels_up)
{
	OffsetVarNodes_context context;

	context.offset = offset;
	context.sublevels_up = sublevels_up;

	/*
	 * Must be prepared to start with a Query or a bare expression tree; if
	 * it's a Query, go straight to query_tree_walker to make sure that
	 * sublevels_up doesn't get incremented prematurely.
	 */
	if (node && IsA(node, Query))
	{
		Query	   *qry = (Query *) node;

		/*
		 * If we are starting at a Query, and sublevels_up is zero, then we
		 * must also fix rangetable indexes in the Query itself --- namely
		 * resultRelation and rowMarks entries.  sublevels_up cannot be zero
		 * when recursing into a subquery, so there's no need to have the same
		 * logic inside OffsetVarNodes_walker.
		 */
		if (sublevels_up == 0)
		{
			ListCell   *l;

			if (qry->resultRelation)
				qry->resultRelation += offset;
			foreach(l, qry->rowMarks)
			{
				RowMarkClause *rc = (RowMarkClause *) lfirst(l);

				rc->rti += offset;
			}
		}
		query_tree_walker(qry, OffsetVarNodes_walker,
						  (void *) &context, 0);
	}
	else
		OffsetVarNodes_walker(node, &context);
}

static Relids
offset_relid_set(Relids relids, int offset)
{
	Relids		result = NULL;
	Relids		tmprelids;
	int			rtindex;

	tmprelids = bms_copy(relids);
	while ((rtindex = bms_first_member(tmprelids)) >= 0)
		result = bms_add_member(result, rtindex + offset);
	bms_free(tmprelids);
	return result;
}

/*
 * ChangeVarNodes - adjust Var nodes for a specific change of RT index
 *
 * Find all Var nodes in the given tree belonging to a specific relation
 * (identified by sublevels_up and rt_index), and change their varno fields
 * to 'new_index'.	The varnoold fields are changed too.  Also, adjust other
 * nodes that contain rangetable indexes, such as RangeTblRef and JoinExpr.
 *
 * NOTE: although this has the form of a walker, we cheat and modify the
 * nodes in-place.	The given expression tree should have been copied
 * earlier to ensure that no unwanted side-effects occur!
 */

typedef struct
{
	int			rt_index;
	int			new_index;
	int			sublevels_up;
} ChangeVarNodes_context;

static bool
ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) node;

		if (var->varlevelsup == context->sublevels_up &&
			var->varno == context->rt_index)
		{
			var->varno = context->new_index;
			var->varnoold = context->new_index;
		}
		return false;
	}
	if (IsA(node, CurrentOfExpr))
	{
		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;

		if (context->sublevels_up == 0 &&
			cexpr->cvarno == context->rt_index)
			cexpr->cvarno = context->new_index;
		return false;
	}
	if (IsA(node, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) node;

		if (context->sublevels_up == 0 &&
			rtr->rtindex == context->rt_index)
			rtr->rtindex = context->new_index;
		/* the subquery itself is visited separately */
		return false;
	}
	if (IsA(node, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) node;

		if (context->sublevels_up == 0 &&
			j->rtindex == context->rt_index)
			j->rtindex = context->new_index;
		/* fall through to examine children */
	}
	if (IsA(node, FlattenedSubLink))
	{
		FlattenedSubLink *fslink = (FlattenedSubLink *) node;

		if (context->sublevels_up == 0)
		{
			fslink->lefthand = adjust_relid_set(fslink->lefthand,
												context->rt_index,
												context->new_index);
			fslink->righthand = adjust_relid_set(fslink->righthand,
												 context->rt_index,
												 context->new_index);
		}
		/* fall through to examine children */
	}
	if (IsA(node, AppendRelInfo))
	{
		AppendRelInfo *appinfo = (AppendRelInfo *) node;

		if (context->sublevels_up == 0)
		{
			if (appinfo->parent_relid == context->rt_index)
				appinfo->parent_relid = context->new_index;
			if (appinfo->child_relid == context->rt_index)
				appinfo->child_relid = context->new_index;
		}
		/* fall through to examine children */
	}
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		bool		result;

		context->sublevels_up++;
		result = query_tree_walker((Query *) node, ChangeVarNodes_walker,
								   (void *) context, 0);
		context->sublevels_up--;
		return result;
	}
	return expression_tree_walker(node, ChangeVarNodes_walker,
								  (void *) context);
}

void
ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
{
	ChangeVarNodes_context context;

	context.rt_index = rt_index;
	context.new_index = new_index;
	context.sublevels_up = sublevels_up;

	/*
	 * Must be prepared to start with a Query or a bare expression tree; if
	 * it's a Query, go straight to query_tree_walker to make sure that
	 * sublevels_up doesn't get incremented prematurely.
	 */
	if (node && IsA(node, Query))
	{
		Query	   *qry = (Query *) node;

		/*
		 * If we are starting at a Query, and sublevels_up is zero, then we
		 * must also fix rangetable indexes in the Query itself --- namely
		 * resultRelation and rowMarks entries.  sublevels_up cannot be zero
		 * when recursing into a subquery, so there's no need to have the same
		 * logic inside ChangeVarNodes_walker.
		 */
		if (sublevels_up == 0)
		{
			ListCell   *l;

			if (qry->resultRelation == rt_index)
				qry->resultRelation = new_index;
			foreach(l, qry->rowMarks)
			{
				RowMarkClause *rc = (RowMarkClause *) lfirst(l);

				if (rc->rti == rt_index)
					rc->rti = new_index;
			}
		}
		query_tree_walker(qry, ChangeVarNodes_walker,
						  (void *) &context, 0);
	}
	else
		ChangeVarNodes_walker(node, &context);
}

/*
 * Substitute newrelid for oldrelid in a Relid set
 */
static Relids
adjust_relid_set(Relids relids, int oldrelid, int newrelid)
{
	if (bms_is_member(oldrelid, relids))
	{
		/* Ensure we have a modifiable copy */
		relids = bms_copy(relids);
		/* Remove old, add new */
		relids = bms_del_member(relids, oldrelid);
		relids = bms_add_member(relids, newrelid);
	}
	return relids;
}

/*
 * IncrementVarSublevelsUp - adjust Var nodes when pushing them down in tree
 *
 * Find all Var nodes in the given tree having varlevelsup >= min_sublevels_up,
 * and add delta_sublevels_up to their varlevelsup value.  This is needed when
 * an expression that's correct for some nesting level is inserted into a
 * subquery.  Ordinarily the initial call has min_sublevels_up == 0 so that
 * all Vars are affected.  The point of min_sublevels_up is that we can
 * increment it when we recurse into a sublink, so that local variables in
 * that sublink are not affected, only outer references to vars that belong
 * to the expression's original query level or parents thereof.
 *
 * Aggref nodes are adjusted similarly.
 *
 * NOTE: although this has the form of a walker, we cheat and modify the
 * Var nodes in-place.	The given expression tree should have been copied
 * earlier to ensure that no unwanted side-effects occur!
 */

typedef struct
{
	int			delta_sublevels_up;
	int			min_sublevels_up;
} IncrementVarSublevelsUp_context;

static bool
IncrementVarSublevelsUp_walker(Node *node,
							   IncrementVarSublevelsUp_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) node;

		if (var->varlevelsup >= context->min_sublevels_up)
			var->varlevelsup += context->delta_sublevels_up;
		return false;			/* done here */
	}
	if (IsA(node, CurrentOfExpr))
	{
		/* this should not happen */
		if (context->min_sublevels_up == 0)
			elog(ERROR, "cannot push down CurrentOfExpr");
		return false;
	}
	if (IsA(node, Aggref))
	{
		Aggref	   *agg = (Aggref *) node;

		if (agg->agglevelsup >= context->min_sublevels_up)
			agg->agglevelsup += context->delta_sublevels_up;
		/* fall through to recurse into argument */
	}
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		bool		result;

		context->min_sublevels_up++;
		result = query_tree_walker((Query *) node,
								   IncrementVarSublevelsUp_walker,
								   (void *) context, 0);
		context->min_sublevels_up--;
		return result;
	}
	return expression_tree_walker(node, IncrementVarSublevelsUp_walker,
								  (void *) context);
}

void
IncrementVarSublevelsUp(Node *node, int delta_sublevels_up,
						int min_sublevels_up)
{
	IncrementVarSublevelsUp_context context;

	context.delta_sublevels_up = delta_sublevels_up;
	context.min_sublevels_up = min_sublevels_up;

	/*
	 * Must be prepared to start with a Query or a bare expression tree; if
	 * it's a Query, we don't want to increment sublevels_up.
	 */
	query_or_expression_tree_walker(node,
									IncrementVarSublevelsUp_walker,
									(void *) &context,
									0);
}

/*
 * IncrementVarSublevelsUp_rtable -
 *	Same as IncrementVarSublevelsUp, but to be invoked on a range table.
 */
void
IncrementVarSublevelsUp_rtable(List *rtable, int delta_sublevels_up,
							   int min_sublevels_up)
{
	IncrementVarSublevelsUp_context context;

	context.delta_sublevels_up = delta_sublevels_up;
	context.min_sublevels_up = min_sublevels_up;

	range_table_walker(rtable,
					   IncrementVarSublevelsUp_walker,
					   (void *) &context,
					   0);
}


/*
 * rangeTableEntry_used - detect whether an RTE is referenced somewhere
 *	in var nodes or join or setOp trees of a query or expression.
 */

typedef struct
{
	int			rt_index;
	int			sublevels_up;
} rangeTableEntry_used_context;

static bool
rangeTableEntry_used_walker(Node *node,
							rangeTableEntry_used_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) node;

		if (var->varlevelsup == context->sublevels_up &&
			var->varno == context->rt_index)
			return true;
		return false;
	}
	if (IsA(node, CurrentOfExpr))
	{
		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;

		if (context->sublevels_up == 0 &&
			cexpr->cvarno == context->rt_index)
			return true;
		return false;
	}
	if (IsA(node, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) node;

		if (rtr->rtindex == context->rt_index &&
			context->sublevels_up == 0)
			return true;
		/* the subquery itself is visited separately */
		return false;
	}
	if (IsA(node, JoinExpr))
	{
		JoinExpr   *j = (JoinExpr *) node;

		if (j->rtindex == context->rt_index &&
			context->sublevels_up == 0)
			return true;
		/* fall through to examine children */
	}
	/* Shouldn't need to handle planner auxiliary nodes here */
	Assert(!IsA(node, FlattenedSubLink));
	Assert(!IsA(node, SpecialJoinInfo));
	Assert(!IsA(node, AppendRelInfo));

	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		bool		result;

		context->sublevels_up++;
		result = query_tree_walker((Query *) node, rangeTableEntry_used_walker,
								   (void *) context, 0);
		context->sublevels_up--;
		return result;
	}
	return expression_tree_walker(node, rangeTableEntry_used_walker,
								  (void *) context);
}

bool
rangeTableEntry_used(Node *node, int rt_index, int sublevels_up)
{
	rangeTableEntry_used_context context;

	context.rt_index = rt_index;
	context.sublevels_up = sublevels_up;

	/*
	 * Must be prepared to start with a Query or a bare expression tree; if
	 * it's a Query, we don't want to increment sublevels_up.
	 */
	return query_or_expression_tree_walker(node,
										   rangeTableEntry_used_walker,
										   (void *) &context,
										   0);
}


/*
 * attribute_used -
 *	Check if a specific attribute number of a RTE is used
 *	somewhere in the query or expression.
 */

typedef struct
{
	int			rt_index;
	int			attno;
	int			sublevels_up;
} attribute_used_context;

static bool
attribute_used_walker(Node *node,
					  attribute_used_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) node;

		if (var->varlevelsup == context->sublevels_up &&
			var->varno == context->rt_index &&
			var->varattno == context->attno)
			return true;
		return false;
	}
	if (IsA(node, Query))
	{
		/* Recurse into subselects */
		bool		result;

		context->sublevels_up++;
		result = query_tree_walker((Query *) node, attribute_used_walker,
								   (void *) context, 0);
		context->sublevels_up--;
		return result;
	}
	return expression_tree_walker(node, attribute_used_walker,
								  (void *) context);
}

bool
attribute_used(Node *node, int rt_index, int attno, int sublevels_up)
{
	attribute_used_context context;

	context.rt_index = rt_index;
	context.attno = attno;
	context.sublevels_up = sublevels_up;

	/*
	 * Must be prepared to start with a Query or a bare expression tree; if
	 * it's a Query, we don't want to increment sublevels_up.
	 */
	return query_or_expression_tree_walker(node,
										   attribute_used_walker,
										   (void *) &context,
										   0);
}


/*
 * If the given Query is an INSERT ... SELECT construct, extract and
 * return the sub-Query node that represents the SELECT part.  Otherwise
 * return the given Query.
 *
 * If subquery_ptr is not NULL, then *subquery_ptr is set to the location
 * of the link to the SELECT subquery inside parsetree, or NULL if not an
 * INSERT ... SELECT.
 *
 * This is a hack needed because transformations on INSERT ... SELECTs that
 * appear in rule actions should be applied to the source SELECT, not to the
 * INSERT part.  Perhaps this can be cleaned up with redesigned querytrees.
 */
Query *
getInsertSelectQuery(Query *parsetree, Query ***subquery_ptr)
{
	Query	   *selectquery;
	RangeTblEntry *selectrte;
	RangeTblRef *rtr;

	if (subquery_ptr)
		*subquery_ptr = NULL;

	if (parsetree == NULL)
		return parsetree;
	if (parsetree->commandType != CMD_INSERT)
		return parsetree;

	/*
	 * Currently, this is ONLY applied to rule-action queries, and so we
	 * expect to find the *OLD* and *NEW* placeholder entries in the given
	 * query.  If they're not there, it must be an INSERT/SELECT in which
	 * they've been pushed down to the SELECT.
	 */
	if (list_length(parsetree->rtable) >= 2 &&
		strcmp(rt_fetch(PRS2_OLD_VARNO, parsetree->rtable)->eref->aliasname,
			   "*OLD*") == 0 &&
		strcmp(rt_fetch(PRS2_NEW_VARNO, parsetree->rtable)->eref->aliasname,
			   "*NEW*") == 0)
		return parsetree;
	Assert(parsetree->jointree && IsA(parsetree->jointree, FromExpr));
	if (list_length(parsetree->jointree->fromlist) != 1)
		elog(ERROR, "expected to find SELECT subquery");
	rtr = (RangeTblRef *) linitial(parsetree->jointree->fromlist);
	Assert(IsA(rtr, RangeTblRef));
	selectrte = rt_fetch(rtr->rtindex, parsetree->rtable);
	selectquery = selectrte->subquery;
	if (!(selectquery && IsA(selectquery, Query) &&
		  selectquery->commandType == CMD_SELECT))
		elog(ERROR, "expected to find SELECT subquery");
	if (list_length(selectquery->rtable) >= 2 &&
		strcmp(rt_fetch(PRS2_OLD_VARNO, selectquery->rtable)->eref->aliasname,
			   "*OLD*") == 0 &&
		strcmp(rt_fetch(PRS2_NEW_VARNO, selectquery->rtable)->eref->aliasname,
			   "*NEW*") == 0)
	{
		if (subquery_ptr)
			*subquery_ptr = &(selectrte->subquery);
		return selectquery;
	}
	elog(ERROR, "could not find rule placeholders");
	return NULL;				/* not reached */
}


/*
 * Add the given qualifier condition to the query's WHERE clause
 */
void
AddQual(Query *parsetree, Node *qual)
{
	Node	   *copy;

	if (qual == NULL)
		return;

	if (parsetree->commandType == CMD_UTILITY)
	{
		/*
		 * There's noplace to put the qual on a utility statement.
		 *
		 * If it's a NOTIFY, silently ignore the qual; this means that the
		 * NOTIFY will execute, whether or not there are any qualifying rows.
		 * While clearly wrong, this is much more useful than refusing to
		 * execute the rule at all, and extra NOTIFY events are harmless for
		 * typical uses of NOTIFY.
		 *
		 * If it isn't a NOTIFY, error out, since unconditional execution of
		 * other utility stmts is unlikely to be wanted.  (This case is not
		 * currently allowed anyway, but keep the test for safety.)
		 */
		if (parsetree->utilityStmt && IsA(parsetree->utilityStmt, NotifyStmt))
			return;
		else
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
			  errmsg("conditional utility statements are not implemented")));
	}

	if (parsetree->setOperations != NULL)
	{
		/*
		 * There's noplace to put the qual on a setop statement, either. (This
		 * could be fixed, but right now the planner simply ignores any qual
		 * condition on a setop query.)
		 */
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
	}

	/* INTERSECT want's the original, but we need to copy - Jan */
	copy = copyObject(qual);

	parsetree->jointree->quals = make_and_qual(parsetree->jointree->quals,
											   copy);

	/*
	 * We had better not have stuck an aggregate into the WHERE clause.
	 */
	Assert(!checkExprHasAggs(copy));

	/*
	 * Make sure query is marked correctly if added qual has sublinks. Need
	 * not search qual when query is already marked.
	 */
	if (!parsetree->hasSubLinks)
		parsetree->hasSubLinks = checkExprHasSubLink(copy);
}


/*
 * Invert the given clause and add it to the WHERE qualifications of the
 * given querytree.  Inversion means "x IS NOT TRUE", not just "NOT x",
 * else we will do the wrong thing when x evaluates to NULL.
 */
void
AddInvertedQual(Query *parsetree, Node *qual)
{
	BooleanTest *invqual;

	if (qual == NULL)
		return;

	/* Need not copy input qual, because AddQual will... */
	invqual = makeNode(BooleanTest);
	invqual->arg = (Expr *) qual;
	invqual->booltesttype = IS_NOT_TRUE;

	AddQual(parsetree, (Node *) invqual);
}


/*
 * ResolveNew - replace Vars with corresponding items from a targetlist
 *
 * Vars matching target_varno and sublevels_up are replaced by the
 * entry with matching resno from targetlist, if there is one.
 * If not, we either change the unmatched Var's varno to update_varno
 * (when event == CMD_UPDATE) or replace it with a constant NULL.
 *
 * The caller must also provide target_rte, the RTE describing the target
 * relation.  This is needed to handle whole-row Vars referencing the target.
 * We expand such Vars into RowExpr constructs.
 *
 * Note: the business with inserted_sublink is needed to update hasSubLinks
 * in subqueries when the replacement adds a subquery inside a subquery.
 * Messy, isn't it?  We do not need to do similar pushups for hasAggs,
 * because it isn't possible for this transformation to insert a level-zero
 * aggregate reference into a subquery --- it could only insert outer aggs.
 */

typedef struct
{
	int			target_varno;
	int			sublevels_up;
	RangeTblEntry *target_rte;
	List	   *targetlist;
	int			event;
	int			update_varno;
	bool		inserted_sublink;
} ResolveNew_context;

static Node *
resolve_one_var(Var *var, ResolveNew_context *context)
{
	TargetEntry *tle;

	tle = get_tle_by_resno(context->targetlist, var->varattno);

	if (tle == NULL)
	{
		/* Failed to find column in insert/update tlist */
		if (context->event == CMD_UPDATE)
		{
			/* For update, just change unmatched var's varno */
			var = (Var *) copyObject(var);
			var->varno = context->update_varno;
			var->varnoold = context->update_varno;
			return (Node *) var;
		}
		else
		{
			/* Otherwise replace unmatched var with a null */
			/* need coerce_to_domain in case of NOT NULL domain constraint */
			return coerce_to_domain((Node *) makeNullConst(var->vartype,
														   var->vartypmod),
									InvalidOid, -1,
									var->vartype,
									COERCE_IMPLICIT_CAST,
									-1,
									false,
									false);
		}
	}
	else
	{
		/* Make a copy of the tlist item to return */
		Node	   *n = copyObject(tle->expr);

		/* Adjust varlevelsup if tlist item is from higher query */
		if (var->varlevelsup > 0)
			IncrementVarSublevelsUp(n, var->varlevelsup, 0);
		/* Report it if we are adding a sublink to query */
		if (!context->inserted_sublink)
			context->inserted_sublink = checkExprHasSubLink(n);
		return n;
	}
}

static Node *
ResolveNew_mutator(Node *node, ResolveNew_context *context)
{
	if (node == NULL)
		return NULL;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) node;
		int			this_varno = (int) var->varno;
		int			this_varlevelsup = (int) var->varlevelsup;

		if (this_varno == context->target_varno &&
			this_varlevelsup == context->sublevels_up)
		{
			if (var->varattno == InvalidAttrNumber)
			{
				/* Must expand whole-tuple reference into RowExpr */
				RowExpr    *rowexpr;
				List	   *fields;

				/*
				 * If generating an expansion for a var of a named rowtype
				 * (ie, this is a plain relation RTE), then we must include
				 * dummy items for dropped columns.  If the var is RECORD (ie,
				 * this is a JOIN), then omit dropped columns.
				 */
				expandRTE(context->target_rte,
						  this_varno, this_varlevelsup,
						  (var->vartype != RECORDOID),
						  NULL, &fields);
				/* Adjust the generated per-field Vars... */
				fields = (List *) ResolveNew_mutator((Node *) fields,
													 context);
				rowexpr = makeNode(RowExpr);
				rowexpr->args = fields;
				rowexpr->row_typeid = var->vartype;
				rowexpr->row_format = COERCE_IMPLICIT_CAST;
				rowexpr->location = -1;

				return (Node *) rowexpr;
			}

			/* Normal case for scalar variable */
			return resolve_one_var(var, context);
		}
		/* otherwise fall through to copy the var normally */
	}
	else if (IsA(node, CurrentOfExpr))
	{
		CurrentOfExpr *cexpr = (CurrentOfExpr *) node;
		int			this_varno = (int) cexpr->cvarno;

		if (this_varno == context->target_varno &&
			context->sublevels_up == 0)
		{
			/*
			 * We get here if a WHERE CURRENT OF expression turns out to apply
			 * to a view.  Someday we might be able to translate the
			 * expression to apply to an underlying table of the view, but
			 * right now it's not implemented.
			 */
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				   errmsg("WHERE CURRENT OF on a view is not implemented")));
		}
		/* otherwise fall through to copy the expr normally */
	}
	else if (IsA(node, Query))
	{
		/* Recurse into RTE subquery or not-yet-planned sublink subquery */
		Query	   *newnode;
		bool		save_inserted_sublink;

		context->sublevels_up++;
		save_inserted_sublink = context->inserted_sublink;
		context->inserted_sublink = false;
		newnode = query_tree_mutator((Query *) node,
									 ResolveNew_mutator,
									 (void *) context,
									 0);
		newnode->hasSubLinks |= context->inserted_sublink;
		context->inserted_sublink = save_inserted_sublink;
		context->sublevels_up--;
		return (Node *) newnode;
	}
	return expression_tree_mutator(node, ResolveNew_mutator,
								   (void *) context);
}

Node *
ResolveNew(Node *node, int target_varno, int sublevels_up,
		   RangeTblEntry *target_rte,
		   List *targetlist, int event, int update_varno)
{
	Node	   *result;
	ResolveNew_context context;

	context.target_varno = target_varno;
	context.sublevels_up = sublevels_up;
	context.target_rte = target_rte;
	context.targetlist = targetlist;
	context.event = event;
	context.update_varno = update_varno;
	context.inserted_sublink = false;

	/*
	 * Must be prepared to start with a Query or a bare expression tree; if
	 * it's a Query, we don't want to increment sublevels_up.
	 */
	result = query_or_expression_tree_mutator(node,
											  ResolveNew_mutator,
											  (void *) &context,
											  0);

	if (context.inserted_sublink)
	{
		if (IsA(result, Query))
			((Query *) result)->hasSubLinks = true;

		/*
		 * Note: if we're called on a non-Query node then it's the caller's
		 * responsibility to update hasSubLinks in the ancestor Query. This is
		 * pretty fragile and perhaps should be rethought ...
		 */
	}

	return result;
}