analyze.c

来自「PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统」· C语言 代码 · 共 2,222 行 · 第 1/5 页

		stmt->actions = newactions;
	}

	/* Close relation, but keep the exclusive lock */
	heap_close(rel, NoLock);

	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/FOR SHARE info available to addRangeTableEntry */
	pstate->p_locking_clause = stmt->lockingClause;

	/* 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);

	qry->intoHasOids = interpretOidsOption(stmt->intoHasOids);

	/* 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.
	 */
	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 || qry->havingQual)
		parseCheckAggregates(pstate, qry);

	if (stmt->lockingClause)
		transformLockingClause(qry, stmt->lockingClause);

	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;
	LockingClause *lockingClause;
	Node	   *node;
	ListCell   *left_tlist,
			   *dtlist;
	List	   *targetvars,
			   *targetnames,
			   *sv_relnamespace,
			   *sv_varnamespace,
			   *sv_rtable;
	RangeTblEntry *jrte;
	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;
	lockingClause = stmt->lockingClause;

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

	/* We don't support FOR UPDATE/SHARE with set ops at the moment. */
	if (lockingClause)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("SELECT FOR UPDATE/SHARE 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;
	left_tlist = list_head(leftmostQuery->targetList);

	foreach(dtlist, sostmt->colTypes)
	{
		Oid			colType = lfirst_oid(dtlist);
		TargetEntry *lefttle = (TargetEntry *) lfirst(left_tlist);
		char	   *colName;
		TargetEntry *tle;
		Expr	   *expr;

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

	/*
	 * 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 varnamespace 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,
									 false);

	sv_rtable = pstate->p_rtable;
	pstate->p_rtable = list_make1(jrte);

	sv_relnamespace = pstate->p_relnamespace;
	pstate->p_relnamespace = NIL;		/* no qualified names allowed */

	sv_varnamespace = pstate->p_varnamespace;
	pstate->p_varnamespace = list_make1(jrte);

	/*
	 * 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 = list_length(qry->targetList);

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

	pstate->p_rtable = sv_rtable;
	pstate->p_relnamespace = sv_relnamespace;
	pstate->p_varnamespace = sv_varnamespace;

	if (tllen != list_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 || qry->havingQual)
		parseCheckAggregates(pstate, qry);

	if (lockingClause)
		transformLockingClause(qry, lockingClause);

	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 FOR UPDATE/SHARE with set ops at the moment. */
	if (stmt->lockingClause)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("SELECT FOR UPDATE/SHARE is not allowed with UNION/INTERSECT/EXCEPT")));

	/*
	 * If an internal node of a set-op tree has ORDER BY, UPDATE, or LIMIT
	 * clauses attached, we need to treat it like a leaf node to generate an
	 * independent sub-Query tree.	Otherwise, it can be represented by a
	 * SetOperationStmt node underneath the parent Query.
	 */
	if (stmt->op == SETOP_NONE)
	{
		Assert(stmt->larg == NULL && stmt->rarg == NULL);
		isLeaf = true;
	}
	else
	{
		Assert(stmt->larg != NULL && stmt->rarg != NULL);
		if (stmt->sortClause || stmt->limitOffset || stmt->limitCount ||
			stmt->lockingClause)
			isLeaf = true;
		else
			isLeaf = false;
	}

	if (isLeaf)
	{
		/* Process leaf SELECT */
		List	   *selectList;
		Query	   *selectQuery;
		char		selectName[32];
		RangeTblEntry *rte;
		RangeTblRef *rtr;

		/*
		 * Transform SelectStmt into a Query.
		 *
		 * Note: previously transformed sub-queries don't affect the parsing
		 * of this sub-query, because they are not in the toplevel pstate's
		 * namespace list.
		 */
		selectList = parse_sub_analyze((Node *) stmt, pstate);

		Assert(list_length(selectList) == 1);
		selectQuery = (Query *) linitial(selectList);
		Assert(IsA(selectQuery, Query));

		/*
		 * Check for bogus references to Vars on the current query level (but
		 * upper-level references are okay). Normally this can't happen
		 * because the namespace will be empty, but it could happen if we are
		 * inside a rule.
		 */
		if (pstate->p_relnamespace || pstate->p_varnamespace)
		{
			if (contain_vars_of_level((Node *) selectQuery, 1))
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
						 errmsg("UNION/INTERSECT/EXCEPT member statement may not refer to other relations of same query level")));
		}

		/*
		 * Make the leaf query be a subquery in the top-level rangetable.
		 */
		snprintf(selectName, sizeof(selectName), "*SELECT* %d",
				 list_length(pstate->p_rtable) + 1);
		rte = addRangeTableEntryForSubquery(pstate,
											selectQuery,
											makeAlias(selectName, NIL),
											false);

		/*
		 * Return a RangeTblRef to replace the SelectStmt in the set-op tree.
		 */
		rtr = makeNode(RangeTblRef);
		/* assume new rte is at end */
		rtr->rtindex = list_length(pstate->p_rtable);
		Assert(rte == rt_fetch(rtr->rtindex, pstate->p_rtable));
		return (Node *) rtr;
	}
	else
	{
		/* Process an internal node (set operation node) */
		SetOperationStmt *op = makeNode(SetOperationStmt);
		List	   *lcoltypes;
		List	   *rcoltypes;
		ListCell   *l;
		ListCell   *r;
		const char *context;

		context = (stmt->op == SETOP_UNION ? "UNION" :
				   (stmt->op == SETOP_INTERSECT ? "INTERSECT" :
					"EXCEPT"));

		op->op = stmt->op;
		op->all = stmt->all;

		/*
		 * Recursively transform the child nodes.
		 */
		op->larg = transformSetOperationTree(pstate, stmt->larg);
		op->rarg = transformSetOperationTree(pstate, stmt->rarg);

		/*
		 * Verify that the two children have the same number of non-junk
		 * columns, and determine the types of the merged output columns.
		 */
		lcoltypes = getSetColTypes(pstate, op->larg);
		rcoltypes = getSetColTypes(pstate, op->rarg);
		if (list_length(lcoltypes) != list_length(rcoltypes))
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("each %s query must have the same number of columns",
						context)));

		op->colTypes = NIL;