setrefs.c

关系型数据库 Postgresql 6.5.2

	foreach(entry, tlist)
	{
		AttrNumber	oattno;

		xtl = lfirst(entry);
		if (IsA(get_expr(xtl), Var))
			oattno = ((Var *) xtl->expr)->varoattno;
		else
			oattno = 0;

		noname = makeTargetEntry(xtl->resdom,
								 (Node *) makeVar(nonameid,
												  xtl->resdom->resno,
												  xtl->resdom->restype,
												  xtl->resdom->restypmod,
												  0,
												  nonameid,
												  oattno));

		t_list = lappend(t_list, noname);
	}
	return t_list;
}

/*---------------------------------------------------------
 *
 * set_result_tlist_references
 *
 * Change the target list of a Result node, so that it correctly
 * addresses the tuples returned by its left tree subplan.
 *
 * NOTE:
 *	1) we ignore the right tree! (in the current implementation
 *	   it is always nil
 *	2) this routine will probably *NOT* work with nested dot
 *	   fields....
 */
static void
set_result_tlist_references(Result *resultNode)
{
	Plan	   *subplan;
	List	   *resultTargetList;
	List	   *subplanTargetList;

	resultTargetList = ((Plan *) resultNode)->targetlist;

	/*
	 * NOTE: we only consider the left tree subplan. This is usually a seq
	 * scan.
	 */
	subplan = ((Plan *) resultNode)->lefttree;
	if (subplan != NULL)
		subplanTargetList = subplan->targetlist;
	else
		subplanTargetList = NIL;

	replace_tlist_with_subplan_refs(resultTargetList,
									(Index) OUTER,
									subplanTargetList);
}

/*---------------------------------------------------------
 *
 * replace_tlist_with_subplan_refs
 *
 * Applies replace_vars_with_subplan_refs() to each entry of a targetlist.
 */
void
replace_tlist_with_subplan_refs(List *tlist,
								Index subvarno,
								List *subplanTargetList)
{
	List	   *t;

	foreach(t, tlist)
	{
		TargetEntry *entry = (TargetEntry *) lfirst(t);

		replace_vars_with_subplan_refs((Node *) get_expr(entry),
									   subvarno, subplanTargetList);
	}
}

/*---------------------------------------------------------
 *
 * replace_vars_with_subplan_refs
 *
 * This routine modifies (destructively!) an expression tree so that all
 * Var nodes reference target nodes of a subplan.  It is used to fix up
 * target expressions of upper-level plan nodes.
 *
 * 'clause': the tree to be fixed
 * 'subvarno': varno to be assigned to all Vars
 * 'subplanTargetList': target list for subplan
 *
 * Afterwards, all Var nodes have varno = subvarno, varattno = resno
 * of corresponding subplan target.
 */
static void
replace_vars_with_subplan_refs(Node *clause,
							   Index subvarno,
							   List *subplanTargetList)
{
	List	   *t;

	if (clause == NULL)
		return;
	if (IsA(clause, Var))
	{

		/*
		 * Ha! A Var node!
		 *
		 * It could be that this varnode has been created by make_groupplan
		 * and is already set up to reference the subplan target list. We
		 * recognize that case by varno = 1, varnoold = -1, varattno =
		 * varoattno, and varlevelsup = 0.	(Probably ought to have an
		 * explicit flag, but this should do for now.)
		 */
		Var		   *var = (Var *) clause;
		TargetEntry *subplanVar;

		if (var->varno == (Index) 1 &&
			var->varnoold == ((Index) -1) &&
			var->varattno == var->varoattno &&
			var->varlevelsup == 0)
			return;				/* OK to leave it alone */

		/* Otherwise it had better be in the subplan list. */
		subplanVar = match_varid(var, subplanTargetList);
		if (!subplanVar)
			elog(ERROR, "replace_vars_with_subplan_refs: variable not in target list");

		/*
		 * Change the varno & varattno fields of the var node.
		 */
		var->varno = subvarno;
		var->varattno = subplanVar->resdom->resno;
	}
	else if (single_node(clause))
	{
		/* do nothing! */
	}
	else if (IsA(clause, Iter))
		replace_vars_with_subplan_refs(((Iter *) clause)->iterexpr,
									   subvarno, subplanTargetList);
	else if (is_subplan(clause))
	{
		foreach(t, ((Expr *) clause)->args)
			replace_vars_with_subplan_refs(lfirst(t),
										   subvarno, subplanTargetList);
		foreach(t, ((SubPlan *) ((Expr *) clause)->oper)->sublink->oper)
			replace_vars_with_subplan_refs(lfirst(((Expr *) lfirst(t))->args),
										   subvarno, subplanTargetList);
	}
	else if (IsA(clause, Expr))
	{

		/*
		 * Recursively scan the arguments of an expression. NOTE: this
		 * must come after is_subplan() case since subplan is a kind of
		 * Expr node.
		 */
		foreach(t, ((Expr *) clause)->args)
			replace_vars_with_subplan_refs(lfirst(t),
										   subvarno, subplanTargetList);
	}
	else if (IsA(clause, Aggref))
		replace_vars_with_subplan_refs(((Aggref *) clause)->target,
									   subvarno, subplanTargetList);
	else if (IsA(clause, ArrayRef))
	{
		ArrayRef   *aref = (ArrayRef *) clause;

		foreach(t, aref->refupperindexpr)
			replace_vars_with_subplan_refs(lfirst(t),
										   subvarno, subplanTargetList);
		foreach(t, aref->reflowerindexpr)
			replace_vars_with_subplan_refs(lfirst(t),
										   subvarno, subplanTargetList);
		replace_vars_with_subplan_refs(aref->refexpr,
									   subvarno, subplanTargetList);
		replace_vars_with_subplan_refs(aref->refassgnexpr,
									   subvarno, subplanTargetList);
	}
	else if (case_clause(clause))
	{
		foreach(t, ((CaseExpr *) clause)->args)
		{
			CaseWhen   *when = (CaseWhen *) lfirst(t);

			replace_vars_with_subplan_refs(when->expr,
										   subvarno, subplanTargetList);
			replace_vars_with_subplan_refs(when->result,
										   subvarno, subplanTargetList);
		}
		replace_vars_with_subplan_refs(((CaseExpr *) clause)->defresult,
									   subvarno, subplanTargetList);
	}
	else
	{
		elog(ERROR, "replace_vars_with_subplan_refs: Cannot handle node type %d",
			 nodeTag(clause));
	}
}

static bool
OperandIsInner(Node *opnd, int inner_relid)
{

	/*
	 * Can be the inner scan if its a varnode or a function and the
	 * inner_relid is equal to the varnode's var number or in the case of
	 * a function the first argument's var number (all args in a
	 * functional index are from the same relation).
	 */
	if (IsA(opnd, Var) &&
		(inner_relid == ((Var *) opnd)->varno))
		return true;
	if (is_funcclause(opnd))
	{
		List	   *firstArg = lfirst(((Expr *) opnd)->args);

		if (IsA(firstArg, Var) &&
			(inner_relid == ((Var *) firstArg)->varno))
			return true;
	}
	return false;
}

/*****************************************************************************
 *
 *****************************************************************************/

/*---------------------------------------------------------
 *
 * set_agg_tlist_references -
 *	  This routine has several responsibilities:
 *	* Update the target list of an Agg node so that it points to
 *	  the tuples returned by its left tree subplan.
 *	* If there is a qual list (from a HAVING clause), similarly update
 *	  vars in it to point to the subplan target list.
 *	* Generate the aggNode->aggs list of Aggref nodes contained in the Agg.
 *
 * The return value is TRUE if all qual clauses include Aggrefs, or FALSE
 * if any do not (caller may choose to raise an error condition).
 */
bool
set_agg_tlist_references(Agg *aggNode)
{
	List	   *subplanTargetList;
	List	   *tl;
	List	   *ql;
	bool		all_quals_ok;

	subplanTargetList = aggNode->plan.lefttree->targetlist;
	aggNode->aggs = NIL;

	foreach(tl, aggNode->plan.targetlist)
	{
		TargetEntry *tle = lfirst(tl);

		replace_vars_with_subplan_refs(tle->expr,
									   (Index) 0,
									   subplanTargetList);
		aggNode->aggs = nconc(pull_agg_clause(tle->expr), aggNode->aggs);
	}

	all_quals_ok = true;
	foreach(ql, aggNode->plan.qual)
	{
		Node	   *qual = lfirst(ql);
		List	   *qualaggs;

		replace_vars_with_subplan_refs(qual,
									   (Index) 0,
									   subplanTargetList);
		qualaggs = pull_agg_clause(qual);
		if (qualaggs == NIL)
			all_quals_ok = false;		/* this qual clause has no agg
										 * functions! */
		else
			aggNode->aggs = nconc(qualaggs, aggNode->aggs);
	}

	return all_quals_ok;
}

/*
 * Make a list of all Aggref nodes contained in the given expression.
 */
static List *
pull_agg_clause(Node *clause)
{
	List	   *agg_list = NIL;
	List	   *t;

	if (clause == NULL)
		return NIL;
	else if (single_node(clause))
		return NIL;
	else if (IsA(clause, Iter))
		return pull_agg_clause(((Iter *) clause)->iterexpr);
	else if (is_subplan(clause))
	{
		SubLink    *sublink = ((SubPlan *) ((Expr *) clause)->oper)->sublink;

		/*
		 * Only the lefthand side of the sublink should be checked for
		 * aggregates to be attached to the aggs list
		 */
		foreach(t, sublink->lefthand)
			agg_list = nconc(pull_agg_clause(lfirst(t)), agg_list);
		/* The first argument of ...->oper has also to be checked */
		foreach(t, sublink->oper)
			agg_list = nconc(pull_agg_clause(lfirst(t)), agg_list);
	}
	else if (IsA(clause, Expr))
	{

		/*
		 * Recursively scan the arguments of an expression. NOTE: this
		 * must come after is_subplan() case since subplan is a kind of
		 * Expr node.
		 */
		foreach(t, ((Expr *) clause)->args)
			agg_list = nconc(pull_agg_clause(lfirst(t)), agg_list);
	}
	else if (IsA(clause, Aggref))
	{
		return lcons(clause,
					 pull_agg_clause(((Aggref *) clause)->target));
	}
	else if (IsA(clause, ArrayRef))
	{
		ArrayRef   *aref = (ArrayRef *) clause;

		foreach(t, aref->refupperindexpr)
			agg_list = nconc(pull_agg_clause(lfirst(t)), agg_list);
		foreach(t, aref->reflowerindexpr)
			agg_list = nconc(pull_agg_clause(lfirst(t)), agg_list);
		agg_list = nconc(pull_agg_clause(aref->refexpr), agg_list);
		agg_list = nconc(pull_agg_clause(aref->refassgnexpr), agg_list);
	}
	else if (case_clause(clause))
	{
		foreach(t, ((CaseExpr *) clause)->args)
		{
			CaseWhen   *when = (CaseWhen *) lfirst(t);

			agg_list = nconc(agg_list, pull_agg_clause(when->expr));
			agg_list = nconc(agg_list, pull_agg_clause(when->result));
		}
		agg_list = nconc(pull_agg_clause(((CaseExpr *) clause)->defresult),
						 agg_list);
	}
	else
	{
		elog(ERROR, "pull_agg_clause: Cannot handle node type %d",
			 nodeTag(clause));
	}

	return agg_list;
}


/*
 * check_having_for_ungrouped_vars takes the havingQual and the list of
 * GROUP BY clauses and checks for subplans in the havingQual that are being
 * passed ungrouped variables as parameters.  In other contexts, ungrouped
 * vars in the havingQual will be detected by the parser (see parse_agg.c,
 * exprIsAggOrGroupCol()).	But that routine currently does not check subplans,
 * because the necessary info is not computed until the planner runs.
 * This ought to be cleaned up someday.
 *
 * NOTE: the havingClause has been cnf-ified, so AND subclauses have been
 * turned into a plain List.  Thus, this routine has to cope with List nodes
 * where the routine above does not...
 */

void
check_having_for_ungrouped_vars(Node *clause, List *groupClause,
								List *targetList)
{
	List	   *t;

	if (clause == NULL)
		return;

	if (IsA(clause, Var))
	{

		/*
		 * Ignore vars elsewhere in the having clause, since the parser
		 * already checked 'em.
		 */
	}
	else if (single_node(clause))
	{
		/* ignore */
	}
	else if (IsA(clause, Iter))
	{
		check_having_for_ungrouped_vars(((Iter *) clause)->iterexpr,
										groupClause, targetList);
	}
	else if (is_subplan(clause))
	{

		/*
		 * The args list of the subplan node represents attributes from
		 * outside passed into the sublink.
		 */
		foreach(t, ((Expr *) clause)->args)
		{
			bool		contained_in_group_clause = false;
			List	   *gl;

			foreach(gl, groupClause)
			{
				if (var_equal(lfirst(t),
							  get_groupclause_expr((GroupClause *)
												lfirst(gl), targetList)))
				{
					contained_in_group_clause = true;
					break;
				}
			}

			if (!contained_in_group_clause)
				elog(ERROR, "Sub-SELECT in HAVING clause must use only GROUPed attributes from outer SELECT");
		}
	}
	else if (IsA(clause, Expr))
	{

		/*
		 * Recursively scan the arguments of an expression. NOTE: this
		 * must come after is_subplan() case since subplan is a kind of
		 * Expr node.
		 */
		foreach(t, ((Expr *) clause)->args)
			check_having_for_ungrouped_vars(lfirst(t), groupClause,
											targetList);
	}
	else if (IsA(clause, List))
	{

		/*
		 * Recursively scan AND subclauses (see NOTE above).
		 */
		foreach(t, ((List *) clause))
			check_having_for_ungrouped_vars(lfirst(t), groupClause,
											targetList);
	}
	else if (IsA(clause, Aggref))
	{
		check_having_for_ungrouped_vars(((Aggref *) clause)->target,
										groupClause, targetList);
	}
	else if (IsA(clause, ArrayRef))
	{
		ArrayRef   *aref = (ArrayRef *) clause;

		/*
		 * This is an arrayref. Recursively call this routine for its
		 * expression and its index expression...
		 */
		foreach(t, aref->refupperindexpr)
			check_having_for_ungrouped_vars(lfirst(t), groupClause,
											targetList);
		foreach(t, aref->reflowerindexpr)
			check_having_for_ungrouped_vars(lfirst(t), groupClause,
											targetList);
		check_having_for_ungrouped_vars(aref->refexpr, groupClause,
										targetList);
		check_having_for_ungrouped_vars(aref->refassgnexpr, groupClause,
										targetList);
	}
	else if (case_clause(clause))
	{
		foreach(t, ((CaseExpr *) clause)->args)
		{
			CaseWhen   *when = (CaseWhen *) lfirst(t);

			check_having_for_ungrouped_vars(when->expr, groupClause,
											targetList);
			check_having_for_ungrouped_vars(when->result, groupClause,
											targetList);
		}
		check_having_for_ungrouped_vars(((CaseExpr *) clause)->defresult,
										groupClause, targetList);
	}
	else
	{
		elog(ERROR, "check_having_for_ungrouped_vars: Cannot handle node type %d",
			 nodeTag(clause));
	}
}