rewritehandler.c

关系型数据库 Postgresql 6.5.2

			break;

		case T_Expr:
			{
				Expr	   *exp = (Expr *) node;

				modifyAggrefUplevel(
									(Node *) (exp->args));
			}
			break;

		case T_Iter:
			{
				Iter	   *iter = (Iter *) node;

				modifyAggrefUplevel(
									(Node *) (iter->iterexpr));
			}
			break;

		case T_ArrayRef:
			{
				ArrayRef   *ref = (ArrayRef *) node;

				modifyAggrefUplevel(
									(Node *) (ref->refupperindexpr));
				modifyAggrefUplevel(
									(Node *) (ref->reflowerindexpr));
				modifyAggrefUplevel(
									(Node *) (ref->refexpr));
				modifyAggrefUplevel(
									(Node *) (ref->refassgnexpr));
			}
			break;

		case T_Var:
			{
				Var		   *var = (Var *) node;

				var->varlevelsup++;
			}
			break;

		case T_Param:
			break;

		case T_Const:
			break;

		case T_List:
			{
				List	   *l;

				foreach(l, (List *) node)
					modifyAggrefUplevel(
										(Node *) lfirst(l));
			}
			break;

		case T_SubLink:
			{
				SubLink    *sub = (SubLink *) node;

				modifyAggrefUplevel(
									(Node *) (sub->lefthand));

				modifyAggrefUplevel(
									(Node *) (sub->oper));

				modifyAggrefUplevel(
									(Node *) (sub->subselect));
			}
			break;

		case T_Query:
			{
				Query	   *qry = (Query *) node;

				modifyAggrefUplevel(
									(Node *) (qry->targetList));

				modifyAggrefUplevel(
									(Node *) (qry->qual));

				modifyAggrefUplevel(
									(Node *) (qry->havingQual));

			}
			break;

		default:
			elog(NOTICE, "unknown node tag %d in modifyAggrefUplevel()", nodeTag(node));
			elog(NOTICE, "Node is: %s", nodeToString(node));
			break;


	}
}


/*
 * modifyAggrefChangeVarnodes -
 *	Change the var nodes in a sublink created for an aggregate column
 *	used in the qualification that is subject of the aggregate
 *	function to point to the correct local RTE.
 */
static void
modifyAggrefChangeVarnodes(Node **nodePtr, int rt_index, int new_index, int sublevels_up)
{
	Node	   *node = *nodePtr;

	if (node == NULL)
		return;

	switch (nodeTag(node))
	{
		case T_TargetEntry:
			{
				TargetEntry *tle = (TargetEntry *) node;

				modifyAggrefChangeVarnodes(
										   (Node **) (&(tle->expr)),
										   rt_index,
										   new_index,
										   sublevels_up);
			}
			break;

		case T_Aggref:
			{
				Aggref	   *aggref = (Aggref *) node;

				modifyAggrefChangeVarnodes(
										   (Node **) (&(aggref->target)),
										   rt_index,
										   new_index,
										   sublevels_up);
			}
			break;

		case T_GroupClause:
			break;

		case T_Expr:
			{
				Expr	   *exp = (Expr *) node;

				modifyAggrefChangeVarnodes(
										   (Node **) (&(exp->args)),
										   rt_index,
										   new_index,
										   sublevels_up);
			}
			break;

		case T_Iter:
			{
				Iter	   *iter = (Iter *) node;

				modifyAggrefChangeVarnodes(
										   (Node **) (&(iter->iterexpr)),
										   rt_index,
										   new_index,
										   sublevels_up);
			}
			break;

		case T_ArrayRef:
			{
				ArrayRef   *ref = (ArrayRef *) node;

				modifyAggrefChangeVarnodes(
									 (Node **) (&(ref->refupperindexpr)),
										   rt_index,
										   new_index,
										   sublevels_up);
				modifyAggrefChangeVarnodes(
									 (Node **) (&(ref->reflowerindexpr)),
										   rt_index,
										   new_index,
										   sublevels_up);
				modifyAggrefChangeVarnodes(
										   (Node **) (&(ref->refexpr)),
										   rt_index,
										   new_index,
										   sublevels_up);
				modifyAggrefChangeVarnodes(
										(Node **) (&(ref->refassgnexpr)),
										   rt_index,
										   new_index,
										   sublevels_up);
			}
			break;

		case T_Var:
			{
				Var		   *var = (Var *) node;

				if (var->varlevelsup == sublevels_up &&
					var->varno == rt_index)
				{
					var = copyObject(var);
					var->varno = new_index;
					var->varnoold = new_index;
					var->varlevelsup = 0;

					*nodePtr = (Node *) var;
				}
			}
			break;

		case T_Param:
			break;

		case T_Const:
			break;

		case T_List:
			{
				List	   *l;

				foreach(l, (List *) node)
					modifyAggrefChangeVarnodes(
											   (Node **) (&lfirst(l)),
											   rt_index,
											   new_index,
											   sublevels_up);
			}
			break;

		case T_SubLink:
			{
				SubLink    *sub = (SubLink *) node;

				modifyAggrefChangeVarnodes(
										   (Node **) (&(sub->lefthand)),
										   rt_index,
										   new_index,
										   sublevels_up);

				modifyAggrefChangeVarnodes(
										   (Node **) (&(sub->oper)),
										   rt_index,
										   new_index,
										   sublevels_up);

				modifyAggrefChangeVarnodes(
										   (Node **) (&(sub->subselect)),
										   rt_index,
										   new_index,
										   sublevels_up + 1);
			}
			break;

		case T_Query:
			{
				Query	   *qry = (Query *) node;

				modifyAggrefChangeVarnodes(
										   (Node **) (&(qry->targetList)),
										   rt_index,
										   new_index,
										   sublevels_up);

				modifyAggrefChangeVarnodes(
										   (Node **) (&(qry->qual)),
										   rt_index,
										   new_index,
										   sublevels_up);

				modifyAggrefChangeVarnodes(
										   (Node **) (&(qry->havingQual)),
										   rt_index,
										   new_index,
										   sublevels_up);
			}
			break;

		default:
			elog(NOTICE, "unknown node tag %d in modifyAggrefChangeVarnodes()", nodeTag(node));
			elog(NOTICE, "Node is: %s", nodeToString(node));
			break;


	}
}


/*
 * modifyAggrefDropQual -
 *	remove the pure aggref clase from a qualification
 */
static void
modifyAggrefDropQual(Node **nodePtr, Node *orignode, Expr *expr)
{
	Node	   *node = *nodePtr;

	if (node == NULL)
		return;

	switch (nodeTag(node))
	{
		case T_Var:
			break;

		case T_Aggref:
			{
				Aggref	   *aggref = (Aggref *) node;
				Aggref	   *oaggref = (Aggref *) orignode;

				modifyAggrefDropQual(
									 (Node **) (&(aggref->target)),
									 (Node *) (oaggref->target),
									 expr);
			}
			break;

		case T_Param:
			break;

		case T_Const:
			break;

		case T_GroupClause:
			break;

		case T_Expr:
			{
				Expr	   *this_expr = (Expr *) node;
				Expr	   *orig_expr = (Expr *) orignode;

				if (orig_expr == expr)
				{
					Const	   *ctrue;

					if (expr->typeOid != BOOLOID)
						elog(ERROR,
							 "aggregate expression in qualification isn't of type bool");
					ctrue = makeNode(Const);
					ctrue->consttype = BOOLOID;
					ctrue->constlen = 1;
					ctrue->constisnull = FALSE;
					ctrue->constvalue = (Datum) TRUE;
					ctrue->constbyval = TRUE;

					*nodePtr = (Node *) ctrue;
				}
				else
					modifyAggrefDropQual(
										 (Node **) (&(this_expr->args)),
										 (Node *) (orig_expr->args),
										 expr);
			}
			break;

		case T_Iter:
			{
				Iter	   *iter = (Iter *) node;
				Iter	   *oiter = (Iter *) orignode;

				modifyAggrefDropQual(
									 (Node **) (&(iter->iterexpr)),
									 (Node *) (oiter->iterexpr),
									 expr);
			}
			break;

		case T_ArrayRef:
			{
				ArrayRef   *ref = (ArrayRef *) node;
				ArrayRef   *oref = (ArrayRef *) orignode;

				modifyAggrefDropQual(
									 (Node **) (&(ref->refupperindexpr)),
									 (Node *) (oref->refupperindexpr),
									 expr);
				modifyAggrefDropQual(
									 (Node **) (&(ref->reflowerindexpr)),
									 (Node *) (oref->reflowerindexpr),
									 expr);
				modifyAggrefDropQual(
									 (Node **) (&(ref->refexpr)),
									 (Node *) (oref->refexpr),
									 expr);
				modifyAggrefDropQual(
									 (Node **) (&(ref->refassgnexpr)),
									 (Node *) (oref->refassgnexpr),
									 expr);
			}
			break;

		case T_List:
			{
				List	   *l;
				List	   *ol = (List *) orignode;
				int			li = 0;

				foreach(l, (List *) node)
				{
					modifyAggrefDropQual(
										 (Node **) (&(lfirst(l))),
										 (Node *) nth(li, ol),
										 expr);
					li++;
				}
			}
			break;

		case T_SubLink:
			{
				SubLink    *sub = (SubLink *) node;
				SubLink    *osub = (SubLink *) orignode;

				modifyAggrefDropQual(
									 (Node **) (&(sub->subselect)),
									 (Node *) (osub->subselect),
									 expr);
			}
			break;

		case T_Query:
			{
				Query	   *qry = (Query *) node;
				Query	   *oqry = (Query *) orignode;

				modifyAggrefDropQual(
									 (Node **) (&(qry->qual)),
									 (Node *) (oqry->qual),
									 expr);

				modifyAggrefDropQual(
									 (Node **) (&(qry->havingQual)),
									 (Node *) (oqry->havingQual),
									 expr);
			}
			break;

		default:
			elog(NOTICE, "unknown node tag %d in modifyAggrefDropQual()", nodeTag(node));
			elog(NOTICE, "Node is: %s", nodeToString(node));
			break;


	}
}


/*
 * modifyAggrefMakeSublink -
 *	Create a sublink node for a qualification expression that
 *	uses an aggregate column of a view
 */
static SubLink *
modifyAggrefMakeSublink(Expr *origexp, Query *parsetree)
{
	SubLink    *sublink;
	Query	   *subquery;
	Node	   *subqual;
	RangeTblEntry *rte;
	Aggref	   *aggref;
	Var		   *target;
	TargetEntry *tle;
	Resdom	   *resdom;
	Expr	   *exp = copyObject(origexp);

	if (nodeTag(nth(0, exp->args)) == T_Aggref)
	{
		if (nodeTag(nth(1, exp->args)) == T_Aggref)
			elog(ERROR, "rewrite: comparision of 2 aggregate columns not supported");
		else
			elog(ERROR, "rewrite: aggregate column of view must be at rigth side in qual");
	}

	aggref = (Aggref *) nth(1, exp->args);
	target = (Var *) (aggref->target);
	rte = (RangeTblEntry *) nth(target->varno - 1, parsetree->rtable);
	tle = makeNode(TargetEntry);
	resdom = makeNode(Resdom);

	aggref->usenulls = TRUE;

	resdom->resno = 1;
	resdom->restype = ((Oper *) (exp->oper))->opresulttype;
	resdom->restypmod = -1;
	resdom->resname = pstrdup("<noname>");
	resdom->reskey = 0;
	resdom->reskeyop = 0;
	resdom->resjunk = false;

	tle->resdom = resdom;
	tle->expr = (Node *) aggref;

	subqual = copyObject(parsetree->qual);
	modifyAggrefDropQual((Node **) &subqual, (Node *) parsetree->qual, origexp);

	sublink = makeNode(SubLink);
	sublink->subLinkType = EXPR_SUBLINK;
	sublink->useor = FALSE;
	sublink->lefthand = lappend(NIL, copyObject(lfirst(exp->args)));
	sublink->oper = lappend(NIL, copyObject(exp));
	sublink->subselect = NULL;

	subquery = makeNode(Query);
	sublink->subselect = (Node *) subquery;

	subquery->commandType = CMD_SELECT;
	subquery->utilityStmt = NULL;
	subquery->resultRelation = 0;
	subquery->into = NULL;
	subquery->isPortal = FALSE;
	subquery->isBinary = FALSE;
	subquery->isTemp = FALSE;
	subquery->unionall = FALSE;
	subquery->uniqueFlag = NULL;
	subquery->sortClause = NULL;
	subquery->rtable = lappend(NIL, rte);
	subquery->targetList = lappend(NIL, tle);
	subquery->qual = subqual;
	subquery->groupClause = NIL;
	subquery->havingQual = NULL;
	subquery->hasAggs = TRUE;
	subquery->hasSubLinks = FALSE;
	subquery->unionClause = NULL;


	modifyAggrefUplevel((Node *) sublink);

	modifyAggrefChangeVarnodes((Node **) &(sublink->lefthand), target->varno,
							   1, target->varlevelsup);
	modifyAggrefChangeVarnodes((Node **) &(sublink->oper), target->varno,
							   1, target->varlevelsup);
	modifyAggrefChangeVarnodes((Node **) &(sublink->subselect), target->varno,
							   1, target->varlevelsup);

	return sublink;
}


/*
 * modifyAggrefQual -
 *	Search for qualification expressions that contain aggregate
 *	functions and substiture them by sublinks. These expressions
 *	originally come from qualifications that use aggregate columns
 *	of a view.
 */
static void
modifyAggrefQual(Node **nodePtr, Query *parsetree)
{
	Node	   *node = *nodePtr;

	if (node == NULL)
		return;

	switch (nodeTag(node))
	{
		case T_Var:
			break;

		case T_Param:
			break;

		case T_Const:
			break;

		case T_GroupClause:
			break;

		case T_Expr:
			{
				Expr	   *exp = (Expr *) node;
				SubLink    *sub;


				if (length(exp->args) != 2)
				{
					modifyAggrefQual(
									 (Node **) (&(exp->args)),
									 parsetree);
					break;
				}

				if (nodeTag(nth(0, exp->args)) != T_Aggref &&
					nodeTag(nth(1, exp->args)) != T_Aggref)
				{

					modifyAggrefQual(
									 (Node **) (&(exp->args)),
									 parsetree);
					break;
				}

				sub = modifyAggrefMakeSublink(exp,
											  parsetree);

				*nodePtr = (Node *) sub;
				parsetree->hasSubLinks = TRUE;
			}