analyze.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,258 行 · 第 1/5 页

			oldrte->checkForRead = false;
			newrte->checkForRead = false;
			addRTEtoQuery(sub_pstate, oldrte, false, true);
			addRTEtoQuery(sub_pstate, newrte, false, true);

			/* Transform the rule action statement */
			top_subqry = transformStmt(sub_pstate, action,
									   extras_before, extras_after);

			/*
			 * We cannot support utility-statement actions (eg NOTIFY)
			 * with nonempty rule WHERE conditions, because there's no way
			 * to make the utility action execute conditionally.
			 */
			if (top_subqry->commandType == CMD_UTILITY &&
				stmt->whereClause != NULL)
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
						 errmsg("rules with WHERE conditions may only have SELECT, INSERT, UPDATE, or DELETE actions")));

			/*
			 * If the action is INSERT...SELECT, OLD/NEW have been pushed
			 * down into the SELECT, and that's what we need to look at.
			 * (Ugly kluge ... try to fix this when we redesign
			 * querytrees.)
			 */
			sub_qry = getInsertSelectQuery(top_subqry, NULL);

			/*
			 * If the sub_qry is a setop, we cannot attach any
			 * qualifications to it, because the planner won't notice
			 * them.  This could perhaps be relaxed someday, but for now,
			 * we may as well reject such a rule immediately.
			 */
			if (sub_qry->setOperations != NULL && stmt->whereClause != NULL)
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));

			/*
			 * Validate action's use of OLD/NEW, qual too
			 */
			has_old =
				rangeTableEntry_used((Node *) sub_qry, PRS2_OLD_VARNO, 0) ||
				rangeTableEntry_used(stmt->whereClause, PRS2_OLD_VARNO, 0);
			has_new =
				rangeTableEntry_used((Node *) sub_qry, PRS2_NEW_VARNO, 0) ||
				rangeTableEntry_used(stmt->whereClause, PRS2_NEW_VARNO, 0);

			switch (stmt->event)
			{
				case CMD_SELECT:
					if (has_old)
						ereport(ERROR,
							 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
							  errmsg("ON SELECT rule may not use OLD")));
					if (has_new)
						ereport(ERROR,
							 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
							  errmsg("ON SELECT rule may not use NEW")));
					break;
				case CMD_UPDATE:
					/* both are OK */
					break;
				case CMD_INSERT:
					if (has_old)
						ereport(ERROR,
							 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
							  errmsg("ON INSERT rule may not use OLD")));
					break;
				case CMD_DELETE:
					if (has_new)
						ereport(ERROR,
							 (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
							  errmsg("ON DELETE rule may not use NEW")));
					break;
				default:
					elog(ERROR, "unrecognized event type: %d",
						 (int) stmt->event);
					break;
			}

			/*
			 * For efficiency's sake, add OLD to the rule action's
			 * jointree only if it was actually referenced in the
			 * statement or qual.
			 *
			 * For INSERT, NEW is not really a relation (only a reference to
			 * the to-be-inserted tuple) and should never be added to the
			 * jointree.
			 *
			 * For UPDATE, we treat NEW as being another kind of reference to
			 * OLD, because it represents references to *transformed*
			 * tuples of the existing relation.  It would be wrong to
			 * enter NEW separately in the jointree, since that would
			 * cause a double join of the updated relation.  It's also
			 * wrong to fail to make a jointree entry if only NEW and not
			 * OLD is mentioned.
			 */
			if (has_old || (has_new && stmt->event == CMD_UPDATE))
			{
				/*
				 * If sub_qry is a setop, manipulating its jointree will
				 * do no good at all, because the jointree is dummy. (This
				 * should be a can't-happen case because of prior tests.)
				 */
				if (sub_qry->setOperations != NULL)
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
				/* hack so we can use addRTEtoQuery() */
				sub_pstate->p_rtable = sub_qry->rtable;
				sub_pstate->p_joinlist = sub_qry->jointree->fromlist;
				addRTEtoQuery(sub_pstate, oldrte, true, false);
				sub_qry->jointree->fromlist = sub_pstate->p_joinlist;
			}

			newactions = lappend(newactions, top_subqry);

			release_pstate_resources(sub_pstate);
			pfree(sub_pstate);
		}

		stmt->actions = newactions;
	}

	return qry;
}


/*
 * transformSelectStmt -
 *	  transforms a Select Statement
 *
 * Note: this is also used for DECLARE CURSOR statements.
 */
static Query *
transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
{
	Query	   *qry = makeNode(Query);
	Node	   *qual;

	qry->commandType = CMD_SELECT;

	/* make FOR UPDATE clause available to addRangeTableEntry */
	pstate->p_forUpdate = stmt->forUpdate;

	/* process the FROM clause */
	transformFromClause(pstate, stmt->fromClause);

	/* transform targetlist */
	qry->targetList = transformTargetList(pstate, stmt->targetList);

	/* handle any SELECT INTO/CREATE TABLE AS spec */
	qry->into = stmt->into;
	if (stmt->intoColNames)
		applyColumnNames(qry->targetList, stmt->intoColNames);

	/* mark column origins */
	markTargetListOrigins(pstate, qry->targetList);

	/* transform WHERE */
	qual = transformWhereClause(pstate, stmt->whereClause, "WHERE");

	/*
	 * Initial processing of HAVING clause is just like WHERE clause.
	 * Additional work will be done in optimizer/plan/planner.c.
	 */
	qry->havingQual = transformWhereClause(pstate, stmt->havingClause,
										   "HAVING");

	/*
	 * Transform sorting/grouping stuff.  Do ORDER BY first because both
	 * transformGroupClause and transformDistinctClause need the results.
	 */
	qry->sortClause = transformSortClause(pstate,
										  stmt->sortClause,
										  qry->targetList,
										  true /* fix unknowns */ );

	qry->groupClause = transformGroupClause(pstate,
											stmt->groupClause,
											qry->targetList,
											qry->sortClause);

	qry->distinctClause = transformDistinctClause(pstate,
												  stmt->distinctClause,
												  qry->targetList,
												  &qry->sortClause);

	qry->limitOffset = transformLimitClause(pstate, stmt->limitOffset,
											"OFFSET");
	qry->limitCount = transformLimitClause(pstate, stmt->limitCount,
										   "LIMIT");

	qry->rtable = pstate->p_rtable;
	qry->jointree = makeFromExpr(pstate->p_joinlist, qual);

	qry->hasSubLinks = pstate->p_hasSubLinks;
	qry->hasAggs = pstate->p_hasAggs;
	if (pstate->p_hasAggs || qry->groupClause)
		parseCheckAggregates(pstate, qry);

	if (stmt->forUpdate != NIL)
		transformForUpdate(qry, stmt->forUpdate);

	return qry;
}

/*
 * transformSetOperationsStmt -
 *	  transforms a set-operations tree
 *
 * A set-operation tree is just a SELECT, but with UNION/INTERSECT/EXCEPT
 * structure to it.  We must transform each leaf SELECT and build up a top-
 * level Query that contains the leaf SELECTs as subqueries in its rangetable.
 * The tree of set operations is converted into the setOperations field of
 * the top-level Query.
 */
static Query *
transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
{
	Query	   *qry = makeNode(Query);
	SelectStmt *leftmostSelect;
	int			leftmostRTI;
	Query	   *leftmostQuery;
	SetOperationStmt *sostmt;
	RangeVar   *into;
	List	   *intoColNames;
	List	   *sortClause;
	Node	   *limitOffset;
	Node	   *limitCount;
	List	   *forUpdate;
	Node	   *node;
	List	   *lefttl,
			   *dtlist,
			   *targetvars,
			   *targetnames,
			   *sv_namespace,
			   *sv_rtable;
	RangeTblEntry *jrte;
	RangeTblRef *jrtr;
	int			tllen;

	qry->commandType = CMD_SELECT;

	/*
	 * Find leftmost leaf SelectStmt; extract the one-time-only items from
	 * it and from the top-level node.
	 */
	leftmostSelect = stmt->larg;
	while (leftmostSelect && leftmostSelect->op != SETOP_NONE)
		leftmostSelect = leftmostSelect->larg;
	Assert(leftmostSelect && IsA(leftmostSelect, SelectStmt) &&
		   leftmostSelect->larg == NULL);
	into = leftmostSelect->into;
	intoColNames = leftmostSelect->intoColNames;

	/* clear them to prevent complaints in transformSetOperationTree() */
	leftmostSelect->into = NULL;
	leftmostSelect->intoColNames = NIL;

	/*
	 * These are not one-time, exactly, but we want to process them here
	 * and not let transformSetOperationTree() see them --- else it'll
	 * just recurse right back here!
	 */
	sortClause = stmt->sortClause;
	limitOffset = stmt->limitOffset;
	limitCount = stmt->limitCount;
	forUpdate = stmt->forUpdate;

	stmt->sortClause = NIL;
	stmt->limitOffset = NULL;
	stmt->limitCount = NULL;
	stmt->forUpdate = NIL;

	/* We don't support forUpdate with set ops at the moment. */
	if (forUpdate)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT")));

	/*
	 * Recursively transform the components of the tree.
	 */
	sostmt = (SetOperationStmt *) transformSetOperationTree(pstate, stmt);
	Assert(sostmt && IsA(sostmt, SetOperationStmt));
	qry->setOperations = (Node *) sostmt;

	/*
	 * Re-find leftmost SELECT (now it's a sub-query in rangetable)
	 */
	node = sostmt->larg;
	while (node && IsA(node, SetOperationStmt))
		node = ((SetOperationStmt *) node)->larg;
	Assert(node && IsA(node, RangeTblRef));
	leftmostRTI = ((RangeTblRef *) node)->rtindex;
	leftmostQuery = rt_fetch(leftmostRTI, pstate->p_rtable)->subquery;
	Assert(leftmostQuery != NULL);

	/*
	 * Generate dummy targetlist for outer query using column names of
	 * leftmost select and common datatypes of topmost set operation. Also
	 * make lists of the dummy vars and their names for use in parsing
	 * ORDER BY.
	 *
	 * Note: we use leftmostRTI as the varno of the dummy variables. It
	 * shouldn't matter too much which RT index they have, as long as they
	 * have one that corresponds to a real RT entry; else funny things may
	 * happen when the tree is mashed by rule rewriting.
	 */
	qry->targetList = NIL;
	targetvars = NIL;
	targetnames = NIL;
	lefttl = leftmostQuery->targetList;
	foreach(dtlist, sostmt->colTypes)
	{
		Oid			colType = lfirsto(dtlist);
		Resdom	   *leftResdom = ((TargetEntry *) lfirst(lefttl))->resdom;
		char	   *colName;
		Resdom	   *resdom;
		Expr	   *expr;

		Assert(!leftResdom->resjunk);
		colName = pstrdup(leftResdom->resname);
		resdom = makeResdom((AttrNumber) pstate->p_next_resno++,
							colType,
							-1,
							colName,
							false);
		expr = (Expr *) makeVar(leftmostRTI,
								leftResdom->resno,
								colType,
								-1,
								0);
		qry->targetList = lappend(qry->targetList,
								  makeTargetEntry(resdom, expr));
		targetvars = lappend(targetvars, expr);
		targetnames = lappend(targetnames, makeString(colName));
		lefttl = lnext(lefttl);
	}

	/*
	 * Handle SELECT INTO/CREATE TABLE AS.
	 *
	 * Any column names from CREATE TABLE AS need to be attached to both the
	 * top level and the leftmost subquery.  We do not do this earlier
	 * because we do *not* want the targetnames list to be affected.
	 */
	qry->into = into;
	if (intoColNames)
	{
		applyColumnNames(qry->targetList, intoColNames);
		applyColumnNames(leftmostQuery->targetList, intoColNames);
	}

	/*
	 * As a first step towards supporting sort clauses that are
	 * expressions using the output columns, generate a namespace entry
	 * that makes the output columns visible.  A Join RTE node is handy
	 * for this, since we can easily control the Vars generated upon
	 * matches.
	 *
	 * Note: we don't yet do anything useful with such cases, but at least
	 * "ORDER BY upper(foo)" will draw the right error message rather than
	 * "foo not found".
	 */
	jrte = addRangeTableEntryForJoin(NULL,
									 targetnames,
									 JOIN_INNER,
									 targetvars,
									 NULL,
									 true);
	jrtr = makeNode(RangeTblRef);
	jrtr->rtindex = 1;			/* only entry in dummy rtable */

	sv_rtable = pstate->p_rtable;
	pstate->p_rtable = makeList1(jrte);

	sv_namespace = pstate->p_namespace;
	pstate->p_namespace = makeList1(jrtr);

	/*
	 * For now, we don't support resjunk sort clauses on the output of a
	 * setOperation tree --- you can only use the SQL92-spec options of
	 * selecting an output column by name or number.  Enforce by checking
	 * that transformSortClause doesn't add any items to tlist.
	 */
	tllen = length(qry->targetList);

	qry->sortClause = transformSortClause(pstate,
										  sortClause,
										  qry->targetList,
									  false /* no unknowns expected */ );

	pstate->p_namespace = sv_namespace;
	pstate->p_rtable = sv_rtable;

	if (tllen != length(qry->targetList))
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("ORDER BY on a UNION/INTERSECT/EXCEPT result must be on one of the result columns")));

	qry->limitOffset = transformLimitClause(pstate, limitOffset,
											"OFFSET");
	qry->limitCount = transformLimitClause(pstate, limitCount,
										   "LIMIT");

	qry->rtable = pstate->p_rtable;
	qry->jointree = makeFromExpr(pstate->p_joinlist, NULL);

	qry->hasSubLinks = pstate->p_hasSubLinks;
	qry->hasAggs = pstate->p_hasAggs;
	if (pstate->p_hasAggs || qry->groupClause)
		parseCheckAggregates(pstate, qry);

	if (forUpdate != NIL)
		transformForUpdate(qry, forUpdate);

	return qry;
}

/*
 * transformSetOperationTree
 *		Recursively transform leaves and internal nodes of a set-op tree
 */
static Node *
transformSetOperationTree(ParseState *pstate, SelectStmt *stmt)
{
	bool		isLeaf;

	Assert(stmt && IsA(stmt, SelectStmt));

	/*
	 * Validity-check both leaf and internal SELECTs for disallowed ops.
	 */
	if (stmt->into)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("INTO is only allowed on first SELECT of UNION/INTERSECT/EXCEPT")));
	/* We don't support forUpdate with set ops at the moment. */
	if (stmt->forUpdate)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT")));

	/*
	 * If an internal node of a set-op tree has ORDER BY, UPDATE, or LIMIT
	 * clauses attached, w